[turbofan] Make Factory::NewNumber() always return the minus_zero_value.

test/unittests/factory-unittest.cc

+// 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.
+
+#include "src/factory.h"
+#include "src/handles-inl.h"
+#include "test/unittests/test-utils.h"
+#include "testing/gmock-support.h"
+
+using testing::BitEq;
+
+namespace v8 {
+namespace internal {
+
+typedef TestWithIsolate FactoryTest;
+
+
+namespace {
+
+const PretenureFlag kPretenureFlags[] = {TENURED, NOT_TENURED};
+
+}  // namespace
+
+
+TEST_F(FactoryTest, MinusZeroValue) {
+  Handle<Object> minus_zero_value = factory()->minus_zero_value();
+  EXPECT_TRUE(minus_zero_value->IsHeapNumber());
+  EXPECT_THAT(minus_zero_value->Number(), BitEq(-0.0));
+}
+
+
+TEST_F(FactoryTest, NewNumberWithMinusZero) {
+  Handle<Object> minus_zero_value = factory()->minus_zero_value();
+  TRACED_FOREACH(PretenureFlag, pretenure_flag, kPretenureFlags) {
+    EXPECT_TRUE(minus_zero_value.is_identical_to(
+        factory()->NewNumber(-0.0, pretenure_flag)));
+  }
+}
+
+
+TEST_F(FactoryTest, NewHeapNumberWithMinusZero) {
+  TRACED_FOREACH(PretenureFlag, pretenure_flag, kPretenureFlags) {
+    Handle<Object> value =
+        factory()->NewHeapNumber(-0.0, IMMUTABLE, pretenure_flag);
+    EXPECT_TRUE(value->IsHeapNumber());
+    EXPECT_THAT(value->Number(), BitEq(-0.0));
+    EXPECT_FALSE(value.is_identical_to(factory()->minus_zero_value()));
+  }
+}
+
+}  // namespace internal
+}  // namespace v8