Add Object::IsNullOrUndefined(Isolate*) helper method

src/objects-inl.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 //
 // Review notes:
 //
 // - The use of macros in these inline functions may seem superfluous
 // but it is absolutely needed to make sure gcc generates optimal
 // code. gcc is not happy when attempting to inline too deep.
 //
@@ skipping 200 matching lines @@
 #define IS_TYPE_FUNCTION_DEF(Type, Value)             \
   bool Object::Is##Type(Isolate* isolate) const {     \
     return this == isolate->heap()->Value();          \
   }                                                   \
   bool HeapObject::Is##Type(Isolate* isolate) const { \
     return this == isolate->heap()->Value();          \
   }
 ODDBALL_LIST(IS_TYPE_FUNCTION_DEF)
 #undef IS_TYPE_FUNCTION_DEF
 
+bool Object::IsNullOrUndefined(Isolate* isolate) const {
+  Heap* heap = isolate->heap();
+  return this == heap->null_value() || this == heap->undefined_value();
+}
+
+bool HeapObject::IsNullOrUndefined(Isolate* isolate) const {
+  Heap* heap = isolate->heap();
+  return this == heap->null_value() || this == heap->undefined_value();
+}
+
 bool HeapObject::IsString() const {
   return map()->instance_type() < FIRST_NONSTRING_TYPE;
 }
 
 bool HeapObject::IsName() const {
   return map()->instance_type() <= LAST_NAME_TYPE;
 }
 
 bool HeapObject::IsUniqueName() const {
   return IsInternalizedString() || IsSymbol();
@@ skipping 8220 matching lines @@
 #undef WRITE_INT64_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 #undef NOBARRIER_READ_BYTE_FIELD
 #undef NOBARRIER_WRITE_BYTE_FIELD
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_OBJECTS_INL_H_