[Oilpan] Add use-after-free detector in Member<>

third_party/WebKit/Source/platform/heap/HeapPage.cpp

Index: third_party/WebKit/Source/platform/heap/HeapPage.cpp
diff --git a/third_party/WebKit/Source/platform/heap/HeapPage.cpp b/third_party/WebKit/Source/platform/heap/HeapPage.cpp
index 10b30f8de75112e2dafff32746ad59ed959836b9..af3d10dc8845f24735d9d26696d84961f4dac419 100644
--- a/third_party/WebKit/Source/platform/heap/HeapPage.cpp
+++ b/third_party/WebKit/Source/platform/heap/HeapPage.cpp
@@ -89,11 +89,16 @@
 namespace blink {
 
 #if ENABLE(ASSERT)
+void HeapObjectHeader::putGcGeneration()
+{
+    m_gcGeneration = Heap::gcGeneration();
+}
+
 NO_SANITIZE_ADDRESS
-void HeapObjectHeader::zapMagic()
+void HeapObjectHeader::clearGcGeneration()
 {
     ASSERT(checkHeader());
-    m_magic = zappedMagic;
+    m_gcGeneration = 0;
 }
 #endif