[es6] Fix prototype chain walk for instanceof.

src/crankshaft/s390/lithium-codegen-s390.cc

 // Copyright 2014 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/s390/lithium-codegen-s390.h"
 
 #include "src/base/bits.h"
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
@@ skipping 2550 matching lines @@
   // Deoptimize if the object needs to be access checked.
   __ LoadlB(object_instance_type,
             FieldMemOperand(object_map, Map::kBitFieldOffset));
   __ TestBit(object_instance_type, Map::kIsAccessCheckNeeded, r0);
   DeoptimizeIf(ne, instr, Deoptimizer::kAccessCheck, cr0);
   // Deoptimize for proxies.
   __ CompareInstanceType(object_map, object_instance_type, JS_PROXY_TYPE);
   DeoptimizeIf(eq, instr, Deoptimizer::kProxy);
   __ LoadP(object_prototype,
            FieldMemOperand(object_map, Map::kPrototypeOffset));
+  __ CompareRoot(object_prototype, Heap::kNullValueRootIndex);
+  EmitFalseBranch(instr, eq);
   __ CmpP(object_prototype, prototype);
   EmitTrueBranch(instr, eq);
-  __ CompareRoot(object_prototype, Heap::kNullValueRootIndex);
-  EmitFalseBranch(instr, eq);
   __ LoadP(object_map,
            FieldMemOperand(object_prototype, HeapObject::kMapOffset));
   __ b(&loop);
 }
 
 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 3118 matching lines @@
   __ LoadP(result,
            FieldMemOperand(scratch, FixedArray::kHeaderSize - kPointerSize));
   __ bind(deferred->exit());
   __ bind(&done);
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8