[es6] Fix prototype chain walk for instanceof.

src/crankshaft/mips64/lithium-codegen-mips64.cc

 // 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.
 
 #include "src/crankshaft/mips64/lithium-codegen-mips64.h"
 
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
 #include "src/crankshaft/hydrogen-osr.h"
 #include "src/crankshaft/mips64/lithium-gap-resolver-mips64.h"
@@ skipping 2518 matching lines @@
   __ And(object_instance_type, object_instance_type,
          Operand(1 << Map::kIsAccessCheckNeeded));
   DeoptimizeIf(ne, instr, Deoptimizer::kAccessCheck, object_instance_type,
                Operand(zero_reg));
   __ lbu(object_instance_type,
          FieldMemOperand(object_map, Map::kInstanceTypeOffset));
   DeoptimizeIf(eq, instr, Deoptimizer::kProxy, object_instance_type,
                Operand(JS_PROXY_TYPE));
 
   __ ld(object_prototype, FieldMemOperand(object_map, Map::kPrototypeOffset));
-  EmitTrueBranch(instr, eq, object_prototype, Operand(prototype));
   __ LoadRoot(at, Heap::kNullValueRootIndex);
   EmitFalseBranch(instr, eq, object_prototype, Operand(at));
+  EmitTrueBranch(instr, eq, object_prototype, Operand(prototype));
   __ Branch(&loop, USE_DELAY_SLOT);
   __ ld(object_map, FieldMemOperand(object_prototype,
                                     HeapObject::kMapOffset));  // In delay slot.
 }
 
 
 void LCodeGen::DoCmpT(LCmpT* instr) {
   DCHECK(ToRegister(instr->context()).is(cp));
   Token::Value op = instr->op();
 
@@ skipping 3209 matching lines @@
   __ ld(result, FieldMemOperand(scratch,
                                 FixedArray::kHeaderSize - kPointerSize));
   __ bind(deferred->exit());
   __ bind(&done);
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8