Add support for postNonNestableIdleTask to the Scheduler and use it in Oilpan

Source/platform/heap/ThreadState.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 578 matching lines @@
 
     if (gcState() != IdleGCScheduled)
         return;
 
     double idleDeltaInSeconds = deadlineSeconds - Platform::current()->monotonicallyIncreasingTime();
     if (idleDeltaInSeconds <= Heap::estimatedMarkingTime()) {
         scheduleIdleGC();
         return;
     }
 
-    // FIXME: Make this precise once idle task is guaranteed to be not in nested loop.
-    Heap::collectGarbage(HeapPointersOnStack, GCWithoutSweep, Heap::IdleGC);
+    Heap::collectGarbage(NoHeapPointersOnStack, GCWithoutSweep, Heap::IdleGC);
 }
 
 void ThreadState::scheduleIdleGC()
 {
     if (!isMainThread())
         return;
 
     if (isSweepingInProgress()) {
         setGCState(SweepingAndIdleGCScheduled);
         return;
     }
 
     if (!m_hasPendingIdleTask) {
         m_hasPendingIdleTask = true;
-        Scheduler::shared()->postIdleTask(FROM_HERE, WTF::bind<double>(&ThreadState::performIdleGC, this));
+        Scheduler::shared()->postNonNestableIdleTask(FROM_HERE, WTF::bind<double>(&ThreadState::performIdleGC, this));
     }
     setGCState(IdleGCScheduled);
 }
 
 void ThreadState::schedulePreciseGC()
 {
     if (isSweepingInProgress()) {
         setGCState(SweepingAndPreciseGCScheduled);
         return;
     }
@@ skipping 573 matching lines @@
         json->beginArray(it->key.ascii().data());
         for (size_t age = 0; age <= maxHeapObjectAge; ++age)
             json->pushInteger(it->value.ages[age]);
         json->endArray();
     }
     TRACE_EVENT_OBJECT_SNAPSHOT_WITH_ID(TRACE_DISABLED_BY_DEFAULT("blink_gc"), statsName, this, json.release());
 }
 #endif
 
 } // namespace blink