Implement Harmony semantics for typeof null (behind a flag).

src/ia32/full-codegen-ia32.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 4087 matching lines @@
     __ j(above_equal, if_false);
     // Check for undetectable objects => false.
     __ test_b(FieldOperand(edx, Map::kBitFieldOffset),
               1 << Map::kIsUndetectable);
     Split(zero, if_true, if_false, fall_through);
   } else if (check->Equals(isolate()->heap()->boolean_symbol())) {
     __ cmp(eax, isolate()->factory()->true_value());
     __ j(equal, if_true);
     __ cmp(eax, isolate()->factory()->false_value());
     Split(equal, if_true, if_false, fall_through);
+  } else if (FLAG_harmony_typeof &&
+             check->Equals(isolate()->heap()->null_symbol())) {
+    __ cmp(eax, isolate()->factory()->null_value());
+    Split(equal, if_true, if_false, fall_through);
   } else if (check->Equals(isolate()->heap()->undefined_symbol())) {
     __ cmp(eax, isolate()->factory()->undefined_value());
     __ j(equal, if_true);
     __ JumpIfSmi(eax, if_false);
     // Check for undetectable objects => true.
     __ mov(edx, FieldOperand(eax, HeapObject::kMapOffset));
     __ movzx_b(ecx, FieldOperand(edx, Map::kBitFieldOffset));
     __ test(ecx, Immediate(1 << Map::kIsUndetectable));
     Split(not_zero, if_true, if_false, fall_through);
   } else if (check->Equals(isolate()->heap()->function_symbol())) {
     __ JumpIfSmi(eax, if_false);
     __ CmpObjectType(eax, FIRST_CALLABLE_SPEC_OBJECT_TYPE, edx);
     Split(above_equal, if_true, if_false, fall_through);
   } else if (check->Equals(isolate()->heap()->object_symbol())) {
     __ JumpIfSmi(eax, if_false);
-    __ cmp(eax, isolate()->factory()->null_value());
-    __ j(equal, if_true);
+    if (!FLAG_harmony_typeof) {
+      __ cmp(eax, isolate()->factory()->null_value());
+      __ j(equal, if_true);
+    }
     __ CmpObjectType(eax, FIRST_NONCALLABLE_SPEC_OBJECT_TYPE, edx);
     __ j(below, if_false);
     __ CmpInstanceType(edx, LAST_NONCALLABLE_SPEC_OBJECT_TYPE);
     __ j(above, if_false);
     // Check for undetectable objects => false.
     __ test_b(FieldOperand(edx, Map::kBitFieldOffset),
               1 << Map::kIsUndetectable);
     Split(zero, if_true, if_false, fall_through);
   } else {
     if (if_false != fall_through) __ jmp(if_false);
@@ skipping 229 matching lines @@
   __ add(Operand(edx), Immediate(masm_->CodeObject()));
   __ jmp(Operand(edx));
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32