Fix bug in r6930 and r6933...

src/x64/full-codegen-x64.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 836 matching lines @@
 
 
 void FullCodeGenerator::VisitForInStatement(ForInStatement* stmt) {
   Comment cmnt(masm_, "[ ForInStatement");
   SetStatementPosition(stmt);
 
   Label loop, exit;
   ForIn loop_statement(this, stmt);
   increment_loop_depth();
 
-  // Load null value as it is used several times below.
-  Register null_value = rdi;
-  __ LoadRoot(null_value, Heap::kNullValueRootIndex);
-
   // Get the object to enumerate over. Both SpiderMonkey and JSC
   // ignore null and undefined in contrast to the specification; see
   // ECMA-262 section 12.6.4.
   VisitForAccumulatorValue(stmt->enumerable());
   __ CompareRoot(rax, Heap::kUndefinedValueRootIndex);
   __ j(equal, &exit);
+  Register null_value = rdi;
+  __ LoadRoot(null_value, Heap::kNullValueRootIndex);
   __ cmpq(rax, null_value);
   __ j(equal, &exit);
 
   // Convert the object to a JS object.
   Label convert, done_convert;
   __ JumpIfSmi(rax, &convert);
   __ CmpObjectType(rax, FIRST_JS_OBJECT_TYPE, rcx);
   __ j(above_equal, &done_convert);
   __ bind(&convert);
   __ push(rax);
@@ skipping 2975 matching lines @@
   __ ret(0);
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64