Oilpan: We need to collect all garbage before shutting down the worker thread

Source/heap/HeapTest.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 285 matching lines @@
                     Heap::collectGarbage(ThreadState::HeapPointersOnStack);
                     gcCount++;
                     atomicIncrement(&m_gcCount);
                 }
 
                 EXPECT_EQ(wrapper->value(), 0x0bbac0de);
                 EXPECT_EQ((*globalPersistent)->value(), 0x0ed0cabb);
             }
             yield();
         }
-        ThreadState::current()->cleanup();
         ThreadState::detach();
         atomicDecrement(&m_threadsToFinish);
     }
 
     volatile int m_gcCount;
     volatile int m_threadsToFinish;
 };
 
 // The accounting for memory includes the memory used by rounding up object
 // sizes. This is done in a different way on 32 bit and 64 bit, so we have to
@@ skipping 2306 matching lines @@
 
 namespace WTF {
 
 // We need the below vector trait specialization for the above HeapVectors to behave correctly wrt. memset, memcmp etc.
 template<> struct VectorTraits<WebCore::VectorObject> : public SimpleClassVectorTraits<WebCore::VectorObject> { };
 template<> struct VectorTraits<WebCore::VectorObjectInheritedTrace> : public SimpleClassVectorTraits<WebCore::VectorObjectInheritedTrace> { };
 template<> struct VectorTraits<WebCore::VectorObjectNoTrace> : public SimpleClassVectorTraits<WebCore::VectorObjectNoTrace> { };
 
 } // WTF namespace