JSON.stringify returns empty when used with performance.timing.
https://bugs.webkit.org/show_bug.cgi?id=151813
<rdar://problem/28066067>

Reviewed by Sam Weinig.

Source/WebCore:

While we are waiting for our bindings generator to handle
"serializer", add a custom toJSON function that allows
performance.timing to be stringified.

Test: fast/dom/webtiming-performance-timing-stringify.html

* CMakeLists.txt: New file added.
* WebCore.xcodeproj/project.pbxproj: New file added.
* bindings/js/JSPerformanceTimingCustom.cpp: Added. Implements toJSON.
(WebCore::JSPerformanceTiming::toJSON):
* page/PerformanceTiming.idl: Add toJSON().

LayoutTests:

* fast/dom/Window/window-properties-performance-expected.txt:
* fast/dom/Window/window-properties-performance-resource-timing-expected.txt:
* fast/dom/webtiming-document-open-expected.txt:
* fast/dom/webtiming-navigate-within-document-expected.txt:
* fast/dom/webtiming-performance-timing-stringify-expected.txt: Added.
* fast/dom/webtiming-performance-timing-stringify.html: Added.
* http/tests/misc/webtiming-cross-origin-and-back1-expected.txt:
* http/tests/misc/webtiming-cross-origin-redirect-expected.txt:
* http/tests/misc/webtiming-no-origin-expected.txt:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@205161 268f45cc-cd09-0410-ab3c-d52691b4dbfc
diff --git a/LayoutTests/fast/dom/webtiming-navigate-within-document-expected.txt b/LayoutTests/fast/dom/webtiming-navigate-within-document-expected.txt
index eb2550f..fa43056 100644
--- a/LayoutTests/fast/dom/webtiming-navigate-within-document-expected.txt
+++ b/LayoutTests/fast/dom/webtiming-navigate-within-document-expected.txt
@@ -22,6 +22,7 @@
 PASS responseEnd is unchanged.
 PASS responseStart is unchanged.
 PASS secureConnectionStart is unchanged.
+PASS toJSON is unchanged.
 PASS unloadEventEnd is unchanged.
 PASS unloadEventStart is unchanged.
 PASS successfullyParsed is true