Add NOTREACHED to HeapObjectHeader::markDead()

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

Index: third_party/WebKit/Source/platform/heap/HeapPage.h
diff --git a/third_party/WebKit/Source/platform/heap/HeapPage.h b/third_party/WebKit/Source/platform/heap/HeapPage.h
index 69d369dc9ef587180b79c1c9ae17260cbd4b794c..8fbc94a78461f9ebb95f6373b040ffee9f05e317 100644
--- a/third_party/WebKit/Source/platform/heap/HeapPage.h
+++ b/third_party/WebKit/Source/platform/heap/HeapPage.h
@@ -925,6 +925,9 @@ NO_SANITIZE_ADDRESS inline bool HeapObjectHeader::isDead() const {
 }
 
 NO_SANITIZE_ADDRESS inline void HeapObjectHeader::markDead() {
+  // A Dead state should not happen in a per-thread heap world.
+  // TODO(haraken): Remove code to handle the Dead state.
+  CHECK(false);
   ASSERT(checkHeader());
   ASSERT(!isMarked());
   m_encoded |= headerDeadBitMask;