[turbofan] Fix typing rule for number addition.

R=jarin@chromium.org
BUG=chromium:629435

Review-Url: https://codereview.chromium.org/2161013002
Cr-Commit-Position: refs/heads/master@{#37859}

src/compiler/operation-typer.cc

@@ -299,7 +299,13 @@ Type* OperationTyper::NumberAdd(Type* lhs, Type* rhs) {
     return Type::Number();
   }
   Type* int_lhs = Type::Intersect(lhs, cache_.kInteger, zone());
+  if (lhs->Maybe(Type::MinusZero())) {
+    int_lhs = Type::Union(int_lhs, cache_.kSingletonZero, zone());
+  }
   Type* int_rhs = Type::Intersect(rhs, cache_.kInteger, zone());
+  if (rhs->Maybe(Type::MinusZero())) {
+    int_rhs = Type::Union(int_rhs, cache_.kSingletonZero, zone());
+  }
   Type* result =
       AddRanger(int_lhs->Min(), int_lhs->Max(), int_rhs->Min(), int_rhs->Max());
   if (lhs->Maybe(Type::NaN()) || rhs->Maybe(Type::NaN())) {

test/mjsunit/regress/regress-crbug-629435.js

+// Copyright 2016 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.
+
+// Flags: --allow-natives-syntax
+
+function bar(v) {
+  v.constructor;
+}
+
+bar([]);
+bar([]);
+
+function foo() {
+  var x = -0;
+  bar(x + 1);
+}
+%OptimizeFunctionOnNextCall(foo);
+foo();