Fix ThreadHeap::isHeapObjectAlive(const T*& ptr) stack overflow.

third_party/WebKit/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 3904 matching lines @@
 }
 
 TEST(HeapTest, Comparisons) {
   Persistent<Bar> barPersistent = Bar::create();
   Persistent<Foo> fooPersistent = Foo::create(barPersistent);
   EXPECT_TRUE(barPersistent != fooPersistent);
   barPersistent = fooPersistent;
   EXPECT_TRUE(barPersistent == fooPersistent);
 }
 
+TEST(HeapTest, CheckConstObjectAlive) {
+  SimpleObject* object = SimpleObject::create();
+  const SimpleObject* constObject = object;
+
+  EXPECT_FALSE(ThreadHeap::isHeapObjectAlive(object));
+  EXPECT_FALSE(ThreadHeap::isHeapObjectAlive(constObject));
+
+  // {

[chcunningham, 2016/11/01 23:26:05]

I'd like to test the isHeapObjectAlive = TRUE case here, but I'm not setting it
up right. If I uncomment this, the test failes at the last two EXPECT_TRUE
calls. Please advise

+  //   TestGCScope scope(BlinkGC::HeapPointersOnStack);
+  //   ThreadHeap& heap = ThreadState::current()->heap();
+  //   CountingVisitor visitor(ThreadState::current());
+
+  //   Address objectAddress = reinterpret_cast<Address>(object);
+  //   EXPECT_TRUE(heap.checkAndMarkPointer(&visitor, objectAddress));
+
+  //   EXPECT_TRUE(ThreadHeap::isHeapObjectAlive(object));
+  //   EXPECT_TRUE(ThreadHeap::isHeapObjectAlive(constObject));
+  // }
+}
+
 TEST(HeapTest, CheckAndMarkPointer) {
   ThreadHeap& heap = ThreadState::current()->heap();
   clearOutOldGarbage();
 
   Vector<Address> objectAddresses;
   Vector<Address> endAddresses;
   Address largeObjectAddress;
   Address largeObjectEndAddress;
   for (int i = 0; i < 10; i++) {
     SimpleObject* object = SimpleObject::create();
@@ skipping 2866 matching lines @@
       "HeapVector");
   static_assert(
       WTF::IsGarbageCollectedType<HeapDeque<Member<IntWrapper>>>::value,
       "HeapDeque");
   static_assert(WTF::IsGarbageCollectedType<
                     HeapTerminatedArray<Member<IntWrapper>>>::value,
                 "HeapTerminatedArray");
 }
 
 }  // namespace blink