Make the GC aware of JSReceiver pointers in LookupResults.

src/isolate.cc

Index: src/isolate.cc
diff --git a/src/isolate.cc b/src/isolate.cc
index 492694e607da48408444a40f7264aa9f33f7b036..2e28e4c1609c99df8f7aad43b4a27ac0ff1e7bd6 100644
--- a/src/isolate.cc
+++ b/src/isolate.cc
@@ -98,6 +98,7 @@ void ThreadLocalTop::InitializeInternal() {
   failed_access_check_callback_ = NULL;
   save_context_ = NULL;
   catcher_ = NULL;
+  top_lookup_result_ = NULL;
 
   // These members are re-initialized later after deserialization
   // is complete.
@@ -480,6 +481,9 @@ void Isolate::Iterate(ObjectVisitor* v, ThreadLocalTop* thread) {
   for (StackFrameIterator it(this, thread); !it.done(); it.Advance()) {
     it.frame()->Iterate(v);
   }
+
+  // Iterate pointers in live lookup results.
+  thread->top_lookup_result_->Iterate(v);
 }