Revert "Use WeakCells in the optimized code map rather than traversing in pause."

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 418df559da2480230dd6e3b6e5d813a6b146f6d9..c510730b8c65f88861d5116264d0a5f9bb832c19 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -2030,10 +2030,7 @@ Object* WeakCell::value() const { return READ_FIELD(this, kValueOffset); }
 
 
 void WeakCell::clear() {
-  // Either the garbage collector is clearing the cell or we are simply
-  // initializing the root empty weak cell.
-  DCHECK(GetHeap()->gc_state() == Heap::MARK_COMPACT ||
-         this == GetHeap()->empty_weak_cell());
+  DCHECK(GetHeap()->gc_state() == Heap::MARK_COMPACT);
   WRITE_FIELD(this, kValueOffset, Smi::FromInt(0));
 }