Oilpan: Validate pointers stored in Persistent

Source/platform/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 3502 matching lines @@
         Persistent<WithWeakMember> h5;
         Heap::collectGarbage(ThreadState::NoHeapPointersOnStack, ThreadState::GCWithSweep, Heap::ForcedGC);
         ASSERT_EQ(1u, Bar::s_live); // h1 is live.
         {
             Bar* h2 = Bar::create();
             Bar* h3 = Bar::create();
             h4 = Weak::create(h2, h3);
             h5 = WithWeakMember::create(h2, h3);
             Heap::collectGarbage(ThreadState::HeapPointersOnStack, ThreadState::GCWithSweep, Heap::ForcedGC);
             EXPECT_EQ(5u, Bar::s_live); // The on-stack pointer keeps h3 alive.
+            EXPECT_FALSE(h3->hasBeenFinalized());
             EXPECT_TRUE(h4->strongIsThere());
             EXPECT_TRUE(h4->weakIsThere());
             EXPECT_TRUE(h5->strongIsThere());
             EXPECT_TRUE(h5->weakIsThere());
         }
         // h3 is collected, weak pointers from h4 and h5 don't keep it alive.
         Heap::collectGarbage(ThreadState::NoHeapPointersOnStack, ThreadState::GCWithSweep, Heap::ForcedGC);
         EXPECT_EQ(4u, Bar::s_live);
         EXPECT_TRUE(h4->strongIsThere());
         EXPECT_FALSE(h4->weakIsThere()); // h3 is gone from weak pointer.
@@ skipping 2577 matching lines @@
 {
     Persistent<ClassWithMember> object = ClassWithMember::create();
     EXPECT_EQ(0, object->traceCount());
     TestMixinAllocatingObject* mixin = TestMixinAllocatingObject::create(object.get());
     EXPECT_TRUE(mixin);
     EXPECT_GT(object->traceCount(), 0);
     EXPECT_GT(mixin->traceCount(), 0);
 }
 
 } // namespace blink