[turbofan] Use CompareNilIC for abstract equality with null/undefined.

src/code-stubs-hydrogen.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/code-stubs.h"
 
 #include "src/bailout-reason.h"
 #include "src/crankshaft/hydrogen.h"
 #include "src/crankshaft/lithium.h"
 #include "src/field-index.h"
@@ skipping 1338 matching lines @@
   Isolate* isolate = graph()->isolate();
   CompareNilICStub* stub = casted_stub();
   HIfContinuation continuation;
   Handle<Map> sentinel_map(isolate->heap()->meta_map());
   Type* type = stub->GetType(zone(), sentinel_map);
   BuildCompareNil(GetParameter(0), type, &continuation, kEmbedMapsViaWeakCells);
   IfBuilder if_nil(this, &continuation);
   if_nil.Then();
   if (continuation.IsFalseReachable()) {
     if_nil.Else();
-    if_nil.Return(graph()->GetConstant0());
+    if_nil.Return(graph()->GetConstantFalse());
   }
   if_nil.End();
-  return continuation.IsTrueReachable()
-      ? graph()->GetConstant1()
-      : graph()->GetConstantUndefined();
+  return continuation.IsTrueReachable() ? graph()->GetConstantTrue()
+                                        : graph()->GetConstantUndefined();
 }
 
 
 Handle<Code> CompareNilICStub::GenerateCode() {
   return DoGenerateCode(this);
 }
 
 
 template <>
 HValue* CodeStubGraphBuilder<BinaryOpICStub>::BuildCodeInitializedStub() {
@@ skipping 990 matching lines @@
   return Pop();
 }
 
 
 Handle<Code> KeyedLoadGenericStub::GenerateCode() {
   return DoGenerateCode(this);
 }
 
 }  // namespace internal
 }  // namespace v8