Revert of Simple BlinkGC heap compaction.

third_party/WebKit/Source/platform/heap/Visitor.cpp

Index: third_party/WebKit/Source/platform/heap/Visitor.cpp
diff --git a/third_party/WebKit/Source/platform/heap/Visitor.cpp b/third_party/WebKit/Source/platform/heap/Visitor.cpp
index 51ff2063c272d8f490fad3a4fa84d4c45212007e..6ace492ae49f8dce67f3ce8f2c7919d615326464 100644
--- a/third_party/WebKit/Source/platform/heap/Visitor.cpp
+++ b/third_party/WebKit/Source/platform/heap/Visitor.cpp
@@ -18,9 +18,6 @@
     case BlinkGC::GCWithSweep:
     case BlinkGC::GCWithoutSweep:
       return WTF::makeUnique<MarkingVisitor<Visitor::GlobalMarking>>(state);
-    case BlinkGC::GCWithSweepCompaction:
-      return WTF::makeUnique<
-          MarkingVisitor<Visitor::GlobalMarkingWithCompaction>>(state);
     case BlinkGC::TakeSnapshot:
       return WTF::makeUnique<MarkingVisitor<Visitor::SnapshotMarking>>(state);
     case BlinkGC::ThreadTerminationGC:
@@ -38,12 +35,13 @@
     : VisitorHelper(state), m_markingMode(markingMode) {
   // See ThreadState::runScheduledGC() why we need to already be in a
   // GCForbiddenScope before any safe point is entered.
-  DCHECK(state->isGCForbidden());
-#if ENABLE(ASSERT)
-  DCHECK(state->checkThread());
-#endif
+  state->enterGCForbiddenScope();
+
+  ASSERT(state->checkThread());
 }
 
-Visitor::~Visitor() {}
+Visitor::~Visitor() {
+  state()->leaveGCForbiddenScope();
+}
 
 }  // namespace blink