Rollback of r12868, r12849 on bleeding_edge.

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index a88b83afeae62836764946ff30ef194f3526eb72..71a169bb71970e9dfe1a72997c9fcce90835559c 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -134,14 +134,6 @@ bool Object::IsFixedArrayBase() {
 }
 
 
-// External objects are not extensible, so the map check is enough.
-bool Object::IsExternal() {
-  return Object::IsHeapObject() &&
-      HeapObject::cast(this)->map() ==
-      HeapObject::cast(this)->GetHeap()->external_map();
-}
-
-
 bool Object::IsInstanceOf(FunctionTemplateInfo* expected) {
   // There is a constraint on the object; check.
   if (!this->IsJSObject()) return false;