Oilpan: handle thread-local weak tracing slightly better.

Source/platform/heap/Heap.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 2279 matching lines @@
     double timeStamp = WTF::currentTimeMS();
 #if ENABLE(GC_PROFILING)
     static_cast<MarkingVisitor<Visitor::GlobalMarking>*>(s_markingVisitor)->objectGraph().clear();
 #endif
 
     // Disallow allocation during garbage collection (but not during the
     // finalization that happens when the gcScope is torn down).
     ThreadState::NoAllocationScope noAllocationScope(state);
 
     preGC();
-    StackFrameDepth::configureStackLimit();
-    ASSERT(StackFrameDepth::isSafeToRecurse());
+
+    StackFrameDepthScope stackDepthScope;
 
     size_t totalObjectSize = Heap::allocatedObjectSize() + Heap::markedObjectSize();
     Heap::resetHeapCounters();
 
     // 1. Trace persistent roots.
     ThreadState::visitPersistentRoots(s_markingVisitor);
 
     // 2. Trace objects reachable from the persistent roots including
     // ephemerons.
     processMarkingStack(s_markingVisitor);
@@ skipping 39 matching lines @@
 void Heap::collectGarbageForTerminatingThread(ThreadState* state)
 {
     // We explicitly do not enter a safepoint while doing thread specific
     // garbage collection since we don't want to allow a global GC at the
     // same time as a thread local GC.
     {
         MarkingVisitor<Visitor::ThreadLocalMarking> markingVisitor;
         ThreadState::NoAllocationScope noAllocationScope(state);
 
         state->preGC();
-        StackFrameDepth::configureStackLimit();
-        ASSERT(StackFrameDepth::isSafeToRecurse());
+        StackFrameDepthScope stackDepthScope;
 
         // 1. Trace the thread local persistent roots. For thread local GCs we
         // don't trace the stack (ie. no conservative scanning) since this is
         // only called during thread shutdown where there should be no objects
         // on the stack.
         // We also assume that orphaned pages have no objects reachable from
         // persistent handles on other threads or CrossThreadPersistents.  The
         // only cases where this could happen is if a subsequent conservative
         // global GC finds a "pointer" on the stack or due to a programming
         // error where an object has a dangling cross-thread pointer to an
@@ skipping 353 matching lines @@
 size_t Heap::s_allocatedObjectSize = 0;
 size_t Heap::s_allocatedSpace = 0;
 size_t Heap::s_markedObjectSize = 0;
 // We don't want to use 0 KB for the initial value because it may end up
 // triggering the first GC of some thread too prematurely.
 size_t Heap::s_estimatedLiveObjectSize = 512 * 1024;
 size_t Heap::s_externalObjectSizeAtLastGC = 0;
 double Heap::s_estimatedMarkingTimePerByte = 0.0;
 
 } // namespace blink