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

src/arm/full-codegen-arm.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 4012 matching lines @@
     __ CompareObjectType(r0, r0, r1, FIRST_NONSTRING_TYPE);
     __ b(ge, if_false);
     __ ldrb(r1, FieldMemOperand(r0, Map::kBitFieldOffset));
     __ tst(r1, Operand(1 << Map::kIsUndetectable));
     Split(eq, if_true, if_false, fall_through);
   } else if (check->Equals(isolate()->heap()->boolean_symbol())) {
     __ CompareRoot(r0, Heap::kTrueValueRootIndex);
     __ b(eq, if_true);
     __ CompareRoot(r0, Heap::kFalseValueRootIndex);
     Split(eq, if_true, if_false, fall_through);
+  } else if (FLAG_harmony_typeof &&
+             check->Equals(isolate()->heap()->null_symbol())) {
+    __ CompareRoot(r0, Heap::kNullValueRootIndex);
+    Split(eq, if_true, if_false, fall_through);
   } else if (check->Equals(isolate()->heap()->undefined_symbol())) {
     __ CompareRoot(r0, Heap::kUndefinedValueRootIndex);
     __ b(eq, if_true);
     __ JumpIfSmi(r0, if_false);
     // Check for undetectable objects => true.
     __ ldr(r0, FieldMemOperand(r0, HeapObject::kMapOffset));
     __ ldrb(r1, FieldMemOperand(r0, Map::kBitFieldOffset));
     __ tst(r1, Operand(1 << Map::kIsUndetectable));
     Split(ne, if_true, if_false, fall_through);
 
   } else if (check->Equals(isolate()->heap()->function_symbol())) {
     __ JumpIfSmi(r0, if_false);
     __ CompareObjectType(r0, r1, r0, FIRST_CALLABLE_SPEC_OBJECT_TYPE);
     Split(ge, if_true, if_false, fall_through);
 
   } else if (check->Equals(isolate()->heap()->object_symbol())) {
     __ JumpIfSmi(r0, if_false);
-    __ CompareRoot(r0, Heap::kNullValueRootIndex);
-    __ b(eq, if_true);
+    if (!FLAG_harmony_typeof) {
+      __ CompareRoot(r0, Heap::kNullValueRootIndex);
+      __ b(eq, if_true);
+    }
     // Check for JS objects => true.
     __ CompareObjectType(r0, r0, r1, FIRST_NONCALLABLE_SPEC_OBJECT_TYPE);
     __ b(lt, if_false);
     __ CompareInstanceType(r0, r1, LAST_NONCALLABLE_SPEC_OBJECT_TYPE);
     __ b(gt, if_false);
     // Check for undetectable objects => false.
     __ ldrb(r1, FieldMemOperand(r0, Map::kBitFieldOffset));
     __ tst(r1, Operand(1 << Map::kIsUndetectable));
     Split(eq, if_true, if_false, fall_through);
   } else {
@@ skipping 230 matching lines @@
   __ mov(r1, Operand(r1, ASR, 1));  // Un-smi-tag value.
   __ add(pc, r1, Operand(masm_->CodeObject()));
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM