Make the GC aware of JSReceiver pointers in LookupResults.

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index 01ab04e60ac144d098e1977d267e80da36ff156a..72b8abf6c64c079c61f66e3e62f9c8e552ebea7e 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -255,6 +255,9 @@ class ThreadLocalTop BASE_EMBEDDED {
   // Call back function to report unsafe JS accesses.
   v8::FailedAccessCheckCallback failed_access_check_callback_;
 
+  // Head of the list of live LookupResults.
+  LookupResult* top_lookup_result_;
+
   // Whether out of memory exceptions should be ignored.
   bool ignore_out_of_memory_;
 
@@ -995,6 +998,13 @@ class Isolate {
   void SetData(void* data) { embedder_data_ = data; }
   void* GetData() { return embedder_data_; }
 
+  LookupResult* top_lookup_result() {
+    return thread_local_top_.top_lookup_result_;
+  }
+  void SetTopLookupResult(LookupResult* top) {
+    thread_local_top_.top_lookup_result_ = top;
+  }
+
  private:
   Isolate();