Simplify pre+post GC ThreadState steps.

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

Index: third_party/WebKit/Source/platform/heap/ThreadState.cpp
diff --git a/third_party/WebKit/Source/platform/heap/ThreadState.cpp b/third_party/WebKit/Source/platform/heap/ThreadState.cpp
index 7821c47460851bc5fc5f97655589dd892f877750..7e4272e495e97a896bdecf9355bebbe5cecce3fb 100644
--- a/third_party/WebKit/Source/platform/heap/ThreadState.cpp
+++ b/third_party/WebKit/Source/platform/heap/ThreadState.cpp
@@ -1468,7 +1468,7 @@ void ThreadState::collectGarbage(BlinkGC::StackState stackState,
       NoAllocationScope noAllocationScope(this);
 
       heap().commitCallbackStacks();
-      heap().preGC();
+      preGC();
 
       StackFrameDepthScope stackDepthScope(&heap().stackFrameDepth());
 
@@ -1534,10 +1534,10 @@ void ThreadState::collectGarbage(BlinkGC::StackState stackState,
       ThreadHeap::reportMemoryUsageHistogram();
       WTF::Partitions::reportMemoryUsageHistogram();
     }
-    heap().postGC(gcType);
+    postGC(gcType);
   }
 
-  heap().preSweep(gcType);
+  preSweep(gcType);
   heap().decommitCallbackStacks();
 }