Enable weak embedded maps in optimized code.

src/mark-compact.h

Index: src/mark-compact.h
diff --git a/src/mark-compact.h b/src/mark-compact.h
index 873534c2fa7838e3b28e7dff947069a8b7a021ab..d8b8a5feda8766d94e73351ff24fd85586df8c7a 100644
--- a/src/mark-compact.h
+++ b/src/mark-compact.h
@@ -853,6 +853,11 @@ class MarkCompactCollector {
   //      or implicit references' groups.
   void ProcessEphemeralMarking(ObjectVisitor* visitor);
 
+  // If the call-site of the top optimized code was not prepared for
+  // deoptimization, then treat the maps in the code as strong pointers,
+  // otherwise a map can die and deoptimize the code.
+  void ProcessTopOptimizedFrame(ObjectVisitor* visitor);
+
   // Mark objects reachable (transitively) from objects in the marking
   // stack.  This function empties the marking stack, but may leave
   // overflowed objects in the heap, in which case the marking stack's