Do not emit pointer information for embedded singleton VM Isolate objects while generating code. Th…

vm/heap.h

Index: vm/heap.h
===================================================================
--- vm/heap.h	(revision 16624)
+++ vm/heap.h	(working copy)
@@ -188,6 +188,8 @@
     stats_.data_[id] = value;
   }
 
+  bool gc_in_progress() const { return gc_in_progress_; }
+
  private:
   class GCStats : public ValueObject {
    public:
@@ -243,6 +245,9 @@
   // This heap is in read-only mode: No allocation is allowed.
   bool read_only_;
 
+  // GC on the heap is in progress.
+  bool gc_in_progress_;
+
   friend class GCTestHelper;
   DISALLOW_COPY_AND_ASSIGN(Heap);
 };