[es6] Fix prototype chain walk for instanceof.

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

 // Copyright 2012 the V8 project authors. All rights reserved.7
 // 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 2399 matching lines @@
          Operand(1 << Map::kIsAccessCheckNeeded));
   DeoptimizeIf(ne, instr, Deoptimizer::kAccessCheck, object_instance_type,
                Operand(zero_reg));
   // Deoptimize for proxies.
   __ lbu(object_instance_type,
          FieldMemOperand(object_map, Map::kInstanceTypeOffset));
   DeoptimizeIf(eq, instr, Deoptimizer::kProxy, object_instance_type,
                Operand(JS_PROXY_TYPE));
 
   __ lw(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(USE_DELAY_SLOT, &loop);
   __ lw(object_map, FieldMemOperand(object_prototype, HeapObject::kMapOffset));
 }
 
 
 void LCodeGen::DoCmpT(LCmpT* instr) {
   DCHECK(ToRegister(instr->context()).is(cp));
   Token::Value op = instr->op();
 
   Handle<Code> ic = CodeFactory::CompareIC(isolate(), op).code();
@@ skipping 3125 matching lines @@
   __ lw(result, FieldMemOperand(scratch,
                                 FixedArray::kHeaderSize - kPointerSize));
   __ bind(deferred->exit());
   __ bind(&done);
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8