[turbofan] Add support for transitioning stores to double fields.

src/transitions.h

Index: src/transitions.h
diff --git a/src/transitions.h b/src/transitions.h
index b979c97df3b13d6d562716fc5240e4441d80bd41..1fcd3860d0bdc552490d42d00a84e97d41dbf26b 100644
--- a/src/transitions.h
+++ b/src/transitions.h
@@ -41,6 +41,14 @@ class TransitionArray: public FixedArray {
 
   static Map* SearchTransition(Map* map, PropertyKind kind, Name* name,
                                PropertyAttributes attributes);
+  static MaybeHandle<Map> SearchTransition(Handle<Map> map, PropertyKind kind,
+                                           Handle<Name> name,
+                                           PropertyAttributes attributes) {
+    if (Map* transition = SearchTransition(*map, kind, *name, attributes)) {
+      return handle(transition);
+    }
+    return MaybeHandle<Map>();
+  }
 
   static Map* SearchSpecial(Map* map, Symbol* name);