diff --git a/LayoutTests/ChangeLog b/LayoutTests/ChangeLog
index 5c5d4b5..c7934ff 100644
--- a/LayoutTests/ChangeLog
+++ b/LayoutTests/ChangeLog
@@ -1,3 +1,26 @@
+2016-06-21  Jiewen Tan  <jiewen_tan@apple.com>
+
+        Unreviewed, rolling out r202302, r202303, r202305, and
+        r202306.
+
+        Roll out the rollouts because of breaking the build.
+
+        Reverted changesets:
+
+        "Unreviewed, rolling out r200678."
+        https://bugs.webkit.org/show_bug.cgi?id=157453
+        http://trac.webkit.org/changeset/202302
+
+        "Unreviewed, rolling out r200619."
+        https://bugs.webkit.org/show_bug.cgi?id=131443
+        http://trac.webkit.org/changeset/202303
+
+        "Unreviewed, attempt to fix the build after r202303."
+        http://trac.webkit.org/changeset/202305
+
+        "Unreviewed, attempt to fix the build after r202303."
+        http://trac.webkit.org/changeset/202306
+
 2016-06-21  Zalan Bujtas  <zalan@apple.com>
 
         LayoutTest tiled-drawing/scrolling/latched-div-with-scroll-snap.html is flaky
diff --git a/LayoutTests/fast/dom/domListEnumeration-expected.txt b/LayoutTests/fast/dom/domListEnumeration-expected.txt
index b26da3f..310a12d 100644
--- a/LayoutTests/fast/dom/domListEnumeration-expected.txt
+++ b/LayoutTests/fast/dom/domListEnumeration-expected.txt
@@ -5,7 +5,7 @@
 
 
 [object NodeList]
-PASS resultArray.length is 11
+PASS resultArray.length is 15
 PASS resultArray[0].i is '0'
 PASS resultArray[0].item is nodeList.item(0)
 PASS resultArray[1].i is '1'
diff --git a/LayoutTests/fast/dom/nodeListIterator-expected.txt b/LayoutTests/fast/dom/nodeListIterator-expected.txt
new file mode 100644
index 0000000..7681562
--- /dev/null
+++ b/LayoutTests/fast/dom/nodeListIterator-expected.txt
@@ -0,0 +1,38 @@
+Testing of NodeList iterable capacities.
+
+On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
+
+
+PASS nodeList.length is 2
+PASS item is children[index++]
+PASS item is children[index++]
+PASS pair[0] is children[0]
+PASS pair[1] is children[1]
+PASS forEachContainer is nodeList
+PASS forEachIndex is index
+PASS node is children[index++]
+PASS forEachContainer is nodeList
+PASS forEachIndex is index
+PASS node is children[index++]
+PASS iterator.next().value is children[0]
+PASS iterator.next().value is children[1]
+PASS end.done is true
+PASS end.value is undefined
+PASS iterator.next().value is children[0]
+PASS iterator.next().value is children[1]
+PASS end.done is true
+PASS end.value is undefined
+PASS pair.length is 2
+PASS pair[0] is 0
+PASS pair[1] is children[0]
+PASS pair.length is 2
+PASS pair[0] is 1
+PASS pair[1] is children[1]
+PASS end.done is true
+PASS end.value is undefined
+PASS end.done is true
+PASS end.value is undefined
+PASS successfullyParsed is true
+
+TEST COMPLETE
+
diff --git a/LayoutTests/fast/dom/nodeListIterator.html b/LayoutTests/fast/dom/nodeListIterator.html
new file mode 100644
index 0000000..82a37b1
--- /dev/null
+++ b/LayoutTests/fast/dom/nodeListIterator.html
@@ -0,0 +1,79 @@
+<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML//EN">
+<html>
+    <head>
+        <script src="../../resources/js-test-pre.js"></script>
+    </head>
+    <body>
+        <script>
+            description('Testing of NodeList iterable capacities.');
+
+            if (window.testRunner)
+                testRunner.dumpAsText();
+
+            var end;
+            function checkEndIterator(iteratorValue) {
+              end = iteratorValue;
+              shouldBe('end.done', 'true');
+              shouldBe('end.value', 'undefined');
+            }
+
+            var testingGround = document.createElement('div');
+            var children = [document.createElement('div'), document.createElement('ol')];
+            testingGround.appendChild(children[0]);
+            testingGround.appendChild(children[1]);
+            document.body.appendChild(testingGround);
+
+            var nodeList = testingGround.childNodes;
+
+            shouldBe("nodeList.length", "2");
+
+            var index = 0;
+            for (var item of nodeList)
+                shouldBe('item', 'children[index++]');
+
+            pair = Array.from(nodeList);
+            shouldBe('pair[0]', 'children[0]');
+            shouldBe('pair[1]', 'children[1]');
+
+            index = 0;
+            var node;
+            var forEachIndex;
+            var forEachContainer;
+            nodeList.forEach(function(n, i, c) {
+                node = n;
+                forEachIndex = i;
+                forEachContainer = c;
+                shouldBe('forEachContainer', 'nodeList');
+                shouldBe('forEachIndex', 'index');
+                shouldBe('node', 'children[index++]');
+            });
+                                                                   
+            var iterator = nodeList.keys();
+            shouldBe('iterator.next().value', 'children[0]');
+            shouldBe('iterator.next().value', 'children[1]');
+            checkEndIterator(iterator.next());
+
+            var iterator = nodeList.values();
+            shouldBe('iterator.next().value', 'children[0]');
+            shouldBe('iterator.next().value', 'children[1]');
+            checkEndIterator(iterator.next());
+
+            var iterator = nodeList.entries();
+            var pair = iterator.next().value;
+            shouldBe('pair.length', '2');
+            shouldBe('pair[0]', '0');
+            shouldBe('pair[1]', 'children[0]');
+            pair = iterator.next().value;
+            shouldBe('pair.length', '2');
+            shouldBe('pair[0]', '1');
+            shouldBe('pair[1]', 'children[1]');
+            checkEndIterator(iterator.next());
+
+            testingGround.appendChild(document.createElement('ul'));
+            testingGround.appendChild(document.createElement('p'));
+            checkEndIterator(iterator.next());
+
+        </script>
+        <script src="../../resources/js-test-post.js"></script>
+    </body>
+</html>
diff --git a/LayoutTests/fast/dom/script-tests/domListEnumeration.js b/LayoutTests/fast/dom/script-tests/domListEnumeration.js
index d614b5b..d60551e 100644
--- a/LayoutTests/fast/dom/script-tests/domListEnumeration.js
+++ b/LayoutTests/fast/dom/script-tests/domListEnumeration.js
@@ -97,7 +97,7 @@
 var nodeList = testingGround.childNodes;
 resultArray = iterateList(nodeList);
 
-shouldBe("resultArray.length", "11");
+shouldBe("resultArray.length", "15");
 shouldBe("resultArray[0].i", "'0'");
 shouldBe("resultArray[0].item", "nodeList.item(0)");
 shouldBe("resultArray[1].i", "'1'");
diff --git a/LayoutTests/fast/text/font-face-set-javascript-expected.txt b/LayoutTests/fast/text/font-face-set-javascript-expected.txt
index 9554d12..99eb125 100644
--- a/LayoutTests/fast/text/font-face-set-javascript-expected.txt
+++ b/LayoutTests/fast/text/font-face-set-javascript-expected.txt
@@ -3,8 +3,11 @@
 PASS new FontFaceSet([fontFace1]).size is 1
 PASS fontFaceSet.status is "loaded"
 PASS item.done is false
-PASS item.value is [fontFace1, fontFace1]
+PASS item.value.length is 2
+PASS item.value[0] is 0
+PASS item.value[1] is fontFace1
 PASS item.done is true
+PASS item.value is undefined
 PASS item.done is false
 PASS item.value is fontFace1
 PASS item.done is true
diff --git a/LayoutTests/fast/text/font-face-set-javascript.html b/LayoutTests/fast/text/font-face-set-javascript.html
index 5489a2d..4e64517 100644
--- a/LayoutTests/fast/text/font-face-set-javascript.html
+++ b/LayoutTests/fast/text/font-face-set-javascript.html
@@ -23,9 +23,12 @@
 var iterator = fontFaceSet.entries();
 var item = iterator.next();
 shouldBeFalse("item.done");
-shouldBe("item.value", "[fontFace1, fontFace1]");
+shouldBe("item.value.length", "2");
+shouldBe("item.value[0]", "0");
+shouldBe("item.value[1]", "fontFace1");
 item = iterator.next();
 shouldBeTrue("item.done");
+shouldBe("item.value", "undefined");
 
 iterator = fontFaceSet.keys();
 item = iterator.next();
diff --git a/Source/WebCore/ChangeLog b/Source/WebCore/ChangeLog
index 7ce65ef..ae35eb6 100644
--- a/Source/WebCore/ChangeLog
+++ b/Source/WebCore/ChangeLog
@@ -1,3 +1,26 @@
+2016-06-21  Jiewen Tan  <jiewen_tan@apple.com>
+
+        Unreviewed, rolling out r202302, r202303, r202305, and
+        r202306.
+
+        Roll out the rollouts because of breaking the build.
+
+        Reverted changesets:
+
+        "Unreviewed, rolling out r200678."
+        https://bugs.webkit.org/show_bug.cgi?id=157453
+        http://trac.webkit.org/changeset/202302
+
+        "Unreviewed, rolling out r200619."
+        https://bugs.webkit.org/show_bug.cgi?id=131443
+        http://trac.webkit.org/changeset/202303
+
+        "Unreviewed, attempt to fix the build after r202303."
+        http://trac.webkit.org/changeset/202305
+
+        "Unreviewed, attempt to fix the build after r202303."
+        http://trac.webkit.org/changeset/202306
+
 2016-06-21  Chris Dumez  <cdumez@apple.com>
 
         Unreviewed, attempt to fix the build after r202303.
diff --git a/Source/WebCore/bindings/js/JSDOMBinding.h b/Source/WebCore/bindings/js/JSDOMBinding.h
index 6947674..c62dbb2 100644
--- a/Source/WebCore/bindings/js/JSDOMBinding.h
+++ b/Source/WebCore/bindings/js/JSDOMBinding.h
@@ -267,7 +267,8 @@
 template<typename T, size_t inlineCapacity> JSC::JSValue jsArray(JSC::ExecState*, JSDOMGlobalObject*, const Vector<T, inlineCapacity>*);
 WEBCORE_EXPORT JSC::JSValue jsArray(JSC::ExecState*, JSDOMGlobalObject*, DOMStringList*);
 
-template<typename Value1, typename Value2> JSC::JSValue jsPair(JSC::ExecState&, JSDOMGlobalObject*, const Value1&, const Value2&);
+JSC::JSValue jsPair(JSC::ExecState&, JSDOMGlobalObject*, JSC::JSValue, JSC::JSValue);
+template<typename FirstType, typename SecondType> JSC::JSValue jsPair(JSC::ExecState&, JSDOMGlobalObject*, const FirstType&, const SecondType&);
 
 RefPtr<JSC::ArrayBufferView> toArrayBufferView(JSC::JSValue);
 RefPtr<JSC::Int8Array> toInt8Array(JSC::JSValue);
@@ -625,14 +626,19 @@
     return jsArray(exec, globalObject, *vector);
 }
 
-template<typename Value1, typename Value2> inline JSC::JSValue jsPair(JSC::ExecState& state, JSDOMGlobalObject* globalObject, const Value1& value1, const Value2& value2)
+inline JSC::JSValue jsPair(JSC::ExecState& state, JSDOMGlobalObject* globalObject, JSC::JSValue value1, JSC::JSValue value2)
 {
     JSC::MarkedArgumentBuffer args;
-    args.append(toJS(&state, globalObject, value1));
-    args.append(toJS(&state, globalObject, value2));
+    args.append(value1);
+    args.append(value2);
     return constructArray(&state, 0, globalObject, args);
 }
 
+template<typename FirstType, typename SecondType> inline JSC::JSValue jsPair(JSC::ExecState& state, JSDOMGlobalObject* globalObject, const FirstType& value1, const SecondType& value2)
+{
+    return jsPair(state, globalObject, toJS(&state, globalObject, value1), toJS(&state, globalObject, value2));
+}
+
 inline RefPtr<JSC::ArrayBufferView> toArrayBufferView(JSC::JSValue value)
 {
     auto* wrapper = JSC::jsDynamicCast<JSC::JSArrayBufferView*>(value);
diff --git a/Source/WebCore/bindings/js/JSDOMIterator.h b/Source/WebCore/bindings/js/JSDOMIterator.h
index 4cad3d3..30372eb 100644
--- a/Source/WebCore/bindings/js/JSDOMIterator.h
+++ b/Source/WebCore/bindings/js/JSDOMIterator.h
@@ -108,14 +108,25 @@
     {
     }
 
+    template<typename IteratorValue> typename std::enable_if<IteratorInspector<IteratorValue>::isMap, JSC::JSValue>::type
+    asJS(JSC::ExecState&, IteratorValue&);
+    template<typename IteratorValue> typename std::enable_if<IteratorInspector<IteratorValue>::isSet, JSC::JSValue>::type
+    asJS(JSC::ExecState&, IteratorValue&);
+
     static void destroy(JSC::JSCell*);
 
-    typename DOMWrapped::Iterator m_iterator;
+    Optional<typename DOMWrapped::Iterator> m_iterator;
     IterationKind m_kind;
+    size_t m_index { 0 };
 };
 
 template<typename JSWrapper>
-JSC::EncodedJSValue createKeyValueIterator(JSC::ExecState& state, IterationKind kind, const char* propertyName)
+JSC::EncodedJSValue iteratorCreate(JSC::ExecState&, IterationKind, const char*);
+template<typename JSWrapper>
+JSC::EncodedJSValue iteratorForEach(JSC::ExecState&, const char*);
+
+template<typename JSWrapper>
+JSC::EncodedJSValue iteratorCreate(JSC::ExecState& state, IterationKind kind, const char* propertyName)
 {
     auto wrapper = JSC::jsDynamicCast<JSWrapper*>(state.thisValue());
     if (UNLIKELY(!wrapper))
@@ -124,30 +135,48 @@
     return JSC::JSValue::encode(JSDOMIterator<JSWrapper>::create(globalObject.vm(), getDOMStructure<JSDOMIterator<JSWrapper>>(globalObject.vm(), globalObject), *wrapper, kind));
 }
 
-template<typename IteratorValue> typename std::enable_if<IteratorInspector<IteratorValue>::isMap, JSC::JSValue>::type
-toJS(JSC::ExecState& state, JSDOMGlobalObject* globalObject, IteratorValue& value, IterationKind kind)
+template<typename JSWrapper>
+template<typename IteratorValue> inline typename std::enable_if<IteratorInspector<IteratorValue>::isMap, JSC::JSValue>::type
+JSDOMIterator<JSWrapper>::asJS(JSC::ExecState& state, IteratorValue& value)
 {
     ASSERT(value);
-    if (kind != IterationKind::KeyValue)
-        return toJS(&state, globalObject, (kind == IterationKind::Key) ? value->key : value->value);
+    if (m_kind != IterationKind::KeyValue)
+        return toJS(&state, globalObject(), (m_kind == IterationKind::Key) ? value->key : value->value);
 
-    return jsPair(state, globalObject, value->key, value->value);
-}
-
-template<typename IteratorValue> typename std::enable_if<IteratorInspector<IteratorValue>::isSet, JSC::JSValue>::type
-toJS(JSC::ExecState& state, JSDOMGlobalObject* globalObject, IteratorValue& value, IterationKind kind)
-{
-    ASSERT(value);
-    JSC::JSValue result = toJS(&state, globalObject, *value);
-    if (kind != IterationKind::KeyValue)
-        return result;
-
-    // FIXME: first pair value should be the index of result.
-    return jsPair(state, globalObject, result, result);
+    return jsPair(state, globalObject(), value->key, value->value);
 }
 
 template<typename JSWrapper>
-JSC::EncodedJSValue keyValueIteratorForEach(JSC::ExecState& state, const char* propertyName)
+template<typename IteratorValue> inline typename std::enable_if<IteratorInspector<IteratorValue>::isSet, JSC::JSValue>::type
+JSDOMIterator<JSWrapper>::asJS(JSC::ExecState& state, IteratorValue& value)
+{
+    ASSERT(value);
+    JSC::JSValue result = toJS(&state, globalObject(), *value);
+    if (m_kind != IterationKind::KeyValue)
+        return result;
+
+    return jsPair(state, globalObject(), JSC::jsNumber(m_index++), result);
+}
+
+template<typename IteratorValue> typename std::enable_if<IteratorInspector<IteratorValue>::isMap, void>::type
+appendForEachArguments(JSC::ExecState& state, JSDOMGlobalObject* globalObject, JSC::MarkedArgumentBuffer& arguments, IteratorValue& value, size_t&)
+{
+    ASSERT(value);
+    arguments.append(toJS(&state, globalObject, value->value));
+    arguments.append(toJS(&state, globalObject, value->key));
+}
+
+template<typename IteratorValue> typename std::enable_if<IteratorInspector<IteratorValue>::isSet, void>::type
+appendForEachArguments(JSC::ExecState& state, JSDOMGlobalObject* globalObject, JSC::MarkedArgumentBuffer& arguments, IteratorValue& value, size_t& index)
+{
+    ASSERT(value);
+    JSC::JSValue argument = toJS(&state, globalObject, *value);
+    arguments.append(argument);
+    arguments.append(JSC::jsNumber(index++));
+}
+
+template<typename JSWrapper>
+JSC::EncodedJSValue iteratorForEach(JSC::ExecState& state, const char* propertyName)
 {
     auto wrapper = JSC::jsDynamicCast<JSWrapper*>(state.thisValue());
     if (UNLIKELY(!wrapper))
@@ -158,11 +187,11 @@
     if (callType == JSC::CallType::None)
         return throwVMTypeError(&state);
 
+    size_t index = 0;
     auto iterator = wrapper->wrapped().createIterator();
     while (auto value = iterator.next()) {
         JSC::MarkedArgumentBuffer arguments;
-        arguments.append(toJS(&state, wrapper->globalObject(), value.value().value));
-        arguments.append(toJS(&state, wrapper->globalObject(), value.value().key));
+        appendForEachArguments(state, wrapper->globalObject(), arguments, value, index);
         arguments.append(wrapper);
         JSC::call(&state, state.argument(0), callType, callData, wrapper, arguments);
         if (state.hadException())
@@ -181,19 +210,13 @@
 template<typename JSWrapper>
 JSC::JSValue JSDOMIterator<JSWrapper>::next(JSC::ExecState& state)
 {
-    auto iteratorValue = m_iterator.next();
-    if (!iteratorValue)
-        return createIteratorResultObject(&state, JSC::jsUndefined(), true);
-
-    JSC::JSValue value;
-    if (m_kind == IterationKind::Value)
-        value = toJS(&state, globalObject(), iteratorValue.value().value);
-    else if (m_kind == IterationKind::Key)
-        value = toJS(&state, globalObject(), iteratorValue.value().key);
-    else
-        value = jsPair(state, globalObject(), iteratorValue.value().key, iteratorValue.value().value);
-
-    return createIteratorResultObject(&state, value, false);
+    if (m_iterator) {
+        auto iteratorValue = m_iterator->next();
+        if (iteratorValue)
+            return createIteratorResultObject(&state, asJS(state, iteratorValue), false);
+        m_iterator = Nullopt;
+    }
+    return createIteratorResultObject(&state, JSC::jsUndefined(), true);
 }
 
 template<typename JSWrapper>
diff --git a/Source/WebCore/bindings/scripts/CodeGeneratorJS.pm b/Source/WebCore/bindings/scripts/CodeGeneratorJS.pm
index b87248b..afb6f76 100644
--- a/Source/WebCore/bindings/scripts/CodeGeneratorJS.pm
+++ b/Source/WebCore/bindings/scripts/CodeGeneratorJS.pm
@@ -4181,10 +4181,6 @@
 {
     my $interface = shift;
 
-    if (not $interface->iterable->isKeyValue) {
-        die "No support yet for set iterators";
-    }
-
     my $interfaceName = $interface->name;
     my $className = "JS$interfaceName";
     my $visibleInterfaceName = $codeGenerator->GetVisibleInterfaceName($interface);
@@ -4211,10 +4207,11 @@
             my $iterationKind = "KeyValue";
             $iterationKind = "Key" if $propertyName eq "keys";
             $iterationKind = "Value" if $propertyName eq "values";
+            $iterationKind = "Value" if $propertyName eq "[Symbol.Iterator]" and not $interface->iterable->isKeyValue;
             push(@implContent,  <<END);
 JSC::EncodedJSValue JSC_HOST_CALL ${functionName}(JSC::ExecState* state)
 {
-    return createKeyValueIterator<${className}>(*state, IterationKind::${iterationKind}, "${propertyName}");
+    return iteratorCreate<${className}>(*state, IterationKind::${iterationKind}, "${propertyName}");
 }
 
 END
@@ -4222,7 +4219,7 @@
             push(@implContent,  <<END);
 JSC::EncodedJSValue JSC_HOST_CALL ${functionName}(JSC::ExecState* state)
 {
-    return keyValueIteratorForEach<${className}>(*state, "${propertyName}");
+    return iteratorForEach<${className}>(*state, "${propertyName}");
 }
 
 END
diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestNode.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestNode.cpp
index a844799..3313d2d 100644
--- a/Source/WebCore/bindings/scripts/test/JS/JSTestNode.cpp
+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestNode.cpp
@@ -24,6 +24,7 @@
 #include "ExceptionCode.h"
 #include "JSDOMBinding.h"
 #include "JSDOMConstructor.h"
+#include "JSDOMIterator.h"
 #include "URL.h"
 #include <runtime/Error.h>
 #include <runtime/JSString.h>
@@ -33,6 +34,14 @@
 
 namespace WebCore {
 
+// Functions
+
+JSC::EncodedJSValue JSC_HOST_CALL jsTestNodePrototypeFunctionSymbolIterator(JSC::ExecState*);
+JSC::EncodedJSValue JSC_HOST_CALL jsTestNodePrototypeFunctionEntries(JSC::ExecState*);
+JSC::EncodedJSValue JSC_HOST_CALL jsTestNodePrototypeFunctionKeys(JSC::ExecState*);
+JSC::EncodedJSValue JSC_HOST_CALL jsTestNodePrototypeFunctionValues(JSC::ExecState*);
+JSC::EncodedJSValue JSC_HOST_CALL jsTestNodePrototypeFunctionForEach(JSC::ExecState*);
+
 // Attributes
 
 JSC::EncodedJSValue jsTestNodeName(JSC::ExecState*, JSC::EncodedJSValue, JSC::PropertyName);
@@ -94,6 +103,10 @@
 {
     { "constructor", DontEnum, NoIntrinsic, { (intptr_t)static_cast<PropertySlot::GetValueFunc>(jsTestNodeConstructor), (intptr_t) static_cast<PutPropertySlot::PutValueFunc>(setJSTestNodeConstructor) } },
     { "name", CustomAccessor, NoIntrinsic, { (intptr_t)static_cast<PropertySlot::GetValueFunc>(jsTestNodeName), (intptr_t) static_cast<PutPropertySlot::PutValueFunc>(setJSTestNodeName) } },
+    { "entries", JSC::Function, NoIntrinsic, { (intptr_t)static_cast<NativeFunction>(jsTestNodePrototypeFunctionEntries), (intptr_t) (0) } },
+    { "keys", JSC::Function, NoIntrinsic, { (intptr_t)static_cast<NativeFunction>(jsTestNodePrototypeFunctionKeys), (intptr_t) (0) } },
+    { "values", JSC::Function, NoIntrinsic, { (intptr_t)static_cast<NativeFunction>(jsTestNodePrototypeFunctionValues), (intptr_t) (0) } },
+    { "forEach", JSC::Function, NoIntrinsic, { (intptr_t)static_cast<NativeFunction>(jsTestNodePrototypeFunctionForEach), (intptr_t) (1) } },
 };
 
 const ClassInfo JSTestNodePrototype::s_info = { "TestNodePrototype", &Base::s_info, 0, CREATE_METHOD_TABLE(JSTestNodePrototype) };
@@ -102,6 +115,7 @@
 {
     Base::finishCreation(vm);
     reifyStaticProperties(vm, JSTestNodePrototypeTableValues, *this);
+    putDirect(vm, vm.propertyNames->iteratorSymbol, JSFunction::create(vm, globalObject(), 0, ASCIILiteral("[Symbol.Iterator]"), jsTestNodePrototypeFunctionSymbolIterator), ReadOnly | DontEnum);
 }
 
 const ClassInfo JSTestNode::s_info = { "TestNode", &Base::s_info, 0, CREATE_METHOD_TABLE(JSTestNode) };
@@ -178,6 +192,40 @@
     return getDOMConstructor<JSTestNodeConstructor>(vm, *jsCast<const JSDOMGlobalObject*>(globalObject));
 }
 
+using TestNodeIterator = JSDOMIterator<JSTestNode>;
+using TestNodeIteratorPrototype = JSDOMIteratorPrototype<JSTestNode>;
+
+template<>
+const JSC::ClassInfo TestNodeIterator::s_info = { "TestNode Iterator", &Base::s_info, 0, CREATE_METHOD_TABLE(TestNodeIterator) };
+
+template<>
+const JSC::ClassInfo TestNodeIteratorPrototype::s_info = { "TestNode Iterator", &Base::s_info, 0, CREATE_METHOD_TABLE(TestNodeIteratorPrototype) };
+
+JSC::EncodedJSValue JSC_HOST_CALL jsTestNodePrototypeFunctionSymbolIterator(JSC::ExecState* state)
+{
+    return iteratorCreate<JSTestNode>(*state, IterationKind::Value, "[Symbol.Iterator]");
+}
+
+JSC::EncodedJSValue JSC_HOST_CALL jsTestNodePrototypeFunctionEntries(JSC::ExecState* state)
+{
+    return iteratorCreate<JSTestNode>(*state, IterationKind::KeyValue, "entries");
+}
+
+JSC::EncodedJSValue JSC_HOST_CALL jsTestNodePrototypeFunctionKeys(JSC::ExecState* state)
+{
+    return iteratorCreate<JSTestNode>(*state, IterationKind::Key, "keys");
+}
+
+JSC::EncodedJSValue JSC_HOST_CALL jsTestNodePrototypeFunctionValues(JSC::ExecState* state)
+{
+    return iteratorCreate<JSTestNode>(*state, IterationKind::Value, "values");
+}
+
+JSC::EncodedJSValue JSC_HOST_CALL jsTestNodePrototypeFunctionForEach(JSC::ExecState* state)
+{
+    return iteratorForEach<JSTestNode>(*state, "forEach");
+}
+
 void JSTestNode::visitChildren(JSCell* cell, SlotVisitor& visitor)
 {
     auto* thisObject = jsCast<JSTestNode*>(cell);
diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestObj.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestObj.cpp
index bb11eea..13c12b9 100644
--- a/Source/WebCore/bindings/scripts/test/JS/JSTestObj.cpp
+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestObj.cpp
@@ -6217,27 +6217,27 @@
 
 JSC::EncodedJSValue JSC_HOST_CALL jsTestObjPrototypeFunctionSymbolIterator(JSC::ExecState* state)
 {
-    return createKeyValueIterator<JSTestObj>(*state, IterationKind::KeyValue, "[Symbol.Iterator]");
+    return iteratorCreate<JSTestObj>(*state, IterationKind::KeyValue, "[Symbol.Iterator]");
 }
 
 JSC::EncodedJSValue JSC_HOST_CALL jsTestObjPrototypeFunctionEntries(JSC::ExecState* state)
 {
-    return createKeyValueIterator<JSTestObj>(*state, IterationKind::KeyValue, "entries");
+    return iteratorCreate<JSTestObj>(*state, IterationKind::KeyValue, "entries");
 }
 
 JSC::EncodedJSValue JSC_HOST_CALL jsTestObjPrototypeFunctionKeys(JSC::ExecState* state)
 {
-    return createKeyValueIterator<JSTestObj>(*state, IterationKind::Key, "keys");
+    return iteratorCreate<JSTestObj>(*state, IterationKind::Key, "keys");
 }
 
 JSC::EncodedJSValue JSC_HOST_CALL jsTestObjPrototypeFunctionValues(JSC::ExecState* state)
 {
-    return createKeyValueIterator<JSTestObj>(*state, IterationKind::Value, "values");
+    return iteratorCreate<JSTestObj>(*state, IterationKind::Value, "values");
 }
 
 JSC::EncodedJSValue JSC_HOST_CALL jsTestObjPrototypeFunctionForEach(JSC::ExecState* state)
 {
-    return keyValueIteratorForEach<JSTestObj>(*state, "forEach");
+    return iteratorForEach<JSTestObj>(*state, "forEach");
 }
 
 void JSTestObj::visitChildren(JSCell* cell, SlotVisitor& visitor)
diff --git a/Source/WebCore/bindings/scripts/test/TestNode.idl b/Source/WebCore/bindings/scripts/test/TestNode.idl
index f3795f1..1e4852a 100644
--- a/Source/WebCore/bindings/scripts/test/TestNode.idl
+++ b/Source/WebCore/bindings/scripts/test/TestNode.idl
@@ -23,5 +23,7 @@
     ExportMacro=WEBCORE_TESTSUPPORT_EXPORT,
 ] interface TestNode : Node {
     attribute DOMString name;
+
+    iterable<TestNode>;
 };
 
diff --git a/Source/WebCore/css/FontFaceSet.cpp b/Source/WebCore/css/FontFaceSet.cpp
index a995a64..e50a3af 100644
--- a/Source/WebCore/css/FontFaceSet.cpp
+++ b/Source/WebCore/css/FontFaceSet.cpp
@@ -76,12 +76,11 @@
 {
 }
 
-Optional<WTF::KeyValuePair<RefPtr<FontFace>, RefPtr<FontFace>>> FontFaceSet::Iterator::next()
+RefPtr<FontFace> FontFaceSet::Iterator::next()
 {
     if (m_index == m_target->size())
-        return Nullopt;
-    RefPtr<FontFace> item = m_target->backing()[m_index++].wrapper();
-    return WTF::KeyValuePair<RefPtr<FontFace>, RefPtr<FontFace>>(item, item);
+        return nullptr;
+    return m_target->backing()[m_index++].wrapper();
 }
 
 FontFaceSet::PendingPromise::PendingPromise(LoadPromise&& promise)
diff --git a/Source/WebCore/css/FontFaceSet.h b/Source/WebCore/css/FontFaceSet.h
index d7fceaa..89ad08d 100644
--- a/Source/WebCore/css/FontFaceSet.h
+++ b/Source/WebCore/css/FontFaceSet.h
@@ -62,7 +62,7 @@
     class Iterator {
     public:
         explicit Iterator(FontFaceSet&);
-        Optional<WTF::KeyValuePair<RefPtr<FontFace>, RefPtr<FontFace>>> next();
+        RefPtr<FontFace> next();
 
     private:
         Ref<FontFaceSet> m_target;
diff --git a/Source/WebCore/css/FontFaceSet.idl b/Source/WebCore/css/FontFaceSet.idl
index 60c98eb..ab5cb89 100644
--- a/Source/WebCore/css/FontFaceSet.idl
+++ b/Source/WebCore/css/FontFaceSet.idl
@@ -35,8 +35,7 @@
     boolean has(FontFace font);
 
     // FIXME: We should add support for the setlike declaration.
-    // As a first step this map iterable declaration should be changed to a set iterable.
-    iterable<FontFace, FontFace>;
+    iterable<FontFace>;
 
     readonly attribute long size;
 
diff --git a/Source/WebCore/dom/NodeList.h b/Source/WebCore/dom/NodeList.h
index 822a892..019bd22 100644
--- a/Source/WebCore/dom/NodeList.h
+++ b/Source/WebCore/dom/NodeList.h
@@ -40,6 +40,17 @@
     virtual unsigned length() const = 0;
     virtual Node* item(unsigned index) const = 0;
 
+    class Iterator {
+    public:
+        explicit Iterator(NodeList& list) : m_list(list) { }
+        Node* next() { return m_list->item(m_index++); }
+
+    private:
+        size_t m_index { 0 };
+        Ref<NodeList> m_list;
+    };
+    Iterator createIterator() { return Iterator(*this); }
+
     // Other methods (not part of DOM)
     virtual bool isLiveNodeList() const { return false; }
     virtual bool isChildNodeList() const { return false; }
diff --git a/Source/WebCore/dom/NodeList.idl b/Source/WebCore/dom/NodeList.idl
index 7ed36ee..0cd146d 100644
--- a/Source/WebCore/dom/NodeList.idl
+++ b/Source/WebCore/dom/NodeList.idl
@@ -27,5 +27,6 @@
 ] interface NodeList {
     getter Node item(unsigned long index);
     readonly attribute unsigned long length;
+    iterable<Node>;
 };