[crankshaft] Handle @@toStringTag accessor correctly for BuildCompareInstruction.

test/mjsunit/compare-known-objects-tostringtag.js

Index: test/mjsunit/compare-known-objects-tostringtag.js
diff --git a/test/mjsunit/compare-known-objects-tostringtag.js b/test/mjsunit/compare-known-objects-tostringtag.js
new file mode 100644
index 0000000000000000000000000000000000000000..81544ca69fa86410f88fbb0ae88261017e0799fb
--- /dev/null
+++ b/test/mjsunit/compare-known-objects-tostringtag.js
@@ -0,0 +1,57 @@
+// Copyright 2015 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 --harmony-tostring
+
+function le(a, b) {
+  return a <= b;
+}
+
+function lt(a, b) {
+  return a < b;
+}
+
+function ge(a, b) {
+  return a >= b;
+}
+
+function gt(a, b) {
+  return a > b;
+}
+
+function test(a, b) {
+  // Check CompareIC for less than or equal of known objects.
+  assertThrows(function() {le(a, a)});
+  assertThrows(function() {le(a, b)});
+  assertThrows(function() {le(b, a)});
+  // Check CompareIC for less than of known objects.
+  assertThrows(function() {lt(a, a)});
+  assertThrows(function() {lt(a, b)});
+  assertThrows(function() {lt(b, a)});
+  // Check CompareIC for greater than or equal of known objects.
+  assertThrows(function() {ge(a, a)});
+  assertThrows(function() {ge(a, b)});
+  assertThrows(function() {ge(b, a)});
+  // Check CompareIC for greater than of known objects.
+  assertThrows(function() {gt(a, a)});
+  assertThrows(function() {gt(a, b)});
+  assertThrows(function() {gt(b, a)});
+}
+
+function O() { }
+Object.defineProperty(O.prototype, Symbol.toStringTag, {
+  get: function() { throw "@@toStringTag called!" }
+});
+
+var obj1 = new O;
+var obj2 = new O;
+
+assertTrue(%HaveSameMap(obj1, obj2));
+test(obj1, obj2);
+test(obj1, obj2);
+%OptimizeFunctionOnNextCall(le);
+%OptimizeFunctionOnNextCall(lt);
+%OptimizeFunctionOnNextCall(ge);
+%OptimizeFunctionOnNextCall(gt);
+test(obj1, obj2);