Add support for dictionary elements to polymorphic crankshaft code.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index c9a0a78ba33882767280a9cb100a33e7ab7a4d30..e75ebfbb022be0abc444f23b16e8bfc10856dedb 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -3946,6 +3946,10 @@ class Map: public HeapObject {
         kind <= JSObject::LAST_EXTERNAL_ARRAY_ELEMENTS_KIND;
   }
 
+  inline bool has_dictionary_elements() {
+    return elements_kind() == JSObject::DICTIONARY_ELEMENTS;
+  }
+
   // Tells whether the map is attached to SharedFunctionInfo
   // (for inobject slack tracking).
   inline void set_attached_to_shared_function_info(bool value);