Merge the Merlin heap tracing to top-of-trunk.

runtime/vm/code_generator.cc

Index: runtime/vm/code_generator.cc
diff --git a/runtime/vm/code_generator.cc b/runtime/vm/code_generator.cc
index 0ab08196e3c6d85af24574f3d2e2be5d1cd50ea1..f9879f655aa72190d00519bd349f88bd3748170e 100644
--- a/runtime/vm/code_generator.cc
+++ b/runtime/vm/code_generator.cc
@@ -1899,4 +1899,20 @@ DEFINE_LEAF_RUNTIME_ENTRY(intptr_t,
 }
 END_LEAF_RUNTIME_ENTRY
 
+
+DEFINE_LEAF_RUNTIME_ENTRY(void,
+                          HeapTraceStore,
+                          RawObject* object,
+                          uword field_addr,
+                          RawObject* value) {
+  if (!(object->IsHeapObject() && value->IsHeapObject())) {
+    return;
+  }
+  HeapTrace* heap_trace = Isolate::Current()->heap()->trace();
+  heap_trace->TraceStoreIntoObject(RawObject::ToAddr(object),
+                                   field_addr,
+                                   RawObject::ToAddr(value));
+}
+END_LEAF_RUNTIME_ENTRY
+
 }  // namespace dart