Generate StoreGlobal stubs with Hydrogen

src/heap.h

Index: src/heap.h
diff --git a/src/heap.h b/src/heap.h
index d254b607b6e756d29245c5d312def4d3f00afaaf..d6f41a84ebd9b2c74f1d1c18afb0356bd85ff5e9 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -261,6 +261,7 @@ namespace internal {
   V(map_field_string, "%map")                                            \
   V(elements_field_string, "%elements")                                  \
   V(length_field_string, "%length")                                      \
+  V(cell_value_string, "%cell_value")                                    \
   V(function_class_string, "Function")                                   \
   V(properties_field_symbol, "%properties")                              \
   V(payload_field_symbol, "%payload")                                    \
@@ -1812,6 +1813,8 @@ class Heap {
   void QueueMemoryChunkForFree(MemoryChunk* chunk);
   void FreeQueuedChunks();
 
+  int gc_count() const { return gc_count_; }
+
   // Completely clear the Instanceof cache (to stop it keeping objects alive
   // around a GC).
   inline void CompletelyClearInstanceofCache();