Rename `slotVisitor` variables to `visitor`.
https://bugs.webkit.org/show_bug.cgi?id=221866

Reviewed by Yusuke Suzuki.

In existing code, we sometimes name a SlotVisitor instance `slotVisitor` and
sometimes just `visitor`.  This patch makes it so that we use `visitor` consistently
everywhere.  This will also reduce the size of the GC verifier patch later.

Also fixed a few typos in comments.

This is a pure refactoring patch.  There are no behavior changes.

* API/JSMarkingConstraintPrivate.cpp:
(JSContextGroupAddMarkingConstraint):
* bytecode/RecordedStatuses.cpp:
(JSC::RecordedStatuses::visitAggregate):
(JSC::RecordedStatuses::markIfCheap):
* dfg/DFGGraph.cpp:
(JSC::DFG::Graph::blocksInPostOrder):
* heap/Heap.cpp:
(JSC::Heap::runBeginPhase):
(JSC::Heap::runFixpointPhase):
(JSC::Heap::runConcurrentPhase):
(JSC::Heap::stopThePeriphery):
(JSC::Heap::resumeThePeriphery):
(JSC::Heap::addCoreConstraints):
(JSC::Heap::performIncrement):
* heap/HeapInlines.h:
(JSC::Heap::forEachSlotVisitor):
* runtime/JSSegmentedVariableObject.cpp:
(JSC::JSSegmentedVariableObject::visitChildren):
* runtime/SamplingProfiler.cpp:
(JSC::SamplingProfiler::visit):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@272830 268f45cc-cd09-0410-ab3c-d52691b4dbfc
diff --git a/Source/JavaScriptCore/runtime/SamplingProfiler.cpp b/Source/JavaScriptCore/runtime/SamplingProfiler.cpp
index ce8fce9..5280981 100644
--- a/Source/JavaScriptCore/runtime/SamplingProfiler.cpp
+++ b/Source/JavaScriptCore/runtime/SamplingProfiler.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2016-2020 Apple Inc. All rights reserved.
+ * Copyright (C) 2016-2021 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -652,11 +652,11 @@
     m_unprocessedStackTraces.clear();
 }
 
-void SamplingProfiler::visit(SlotVisitor& slotVisitor)
+void SamplingProfiler::visit(SlotVisitor& visitor)
 {
     RELEASE_ASSERT(m_lock.isLocked());
     for (JSCell* cell : m_liveCellPointers)
-        slotVisitor.appendUnbarriered(cell);
+        visitor.appendUnbarriered(cell);
 }
 
 void SamplingProfiler::shutdown()