Fix handling of -0.0 in IsInt32/IsUInt32

R=ager@chromium.org
BUG=
TEST=

Review URL: http://codereview.chromium.org/9169009

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@10361 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/api.cc

-// Copyright 2011 the V8 project authors. All rights reserved.
+// Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
@@ -2165,6 +2165,11 @@ bool Value::IsInt32() const {
   if (obj->IsSmi()) return true;
   if (obj->IsNumber()) {
     double value = obj->Number();
+    static const i::DoubleRepresentation minus_zero(-0.0);
+    i::DoubleRepresentation rep(value);
+    if (rep.bits == minus_zero.bits) {
+      return false;
+    }
     return i::FastI2D(i::FastD2I(value)) == value;
   }
   return false;
@@ -2177,6 +2182,11 @@ bool Value::IsUint32() const {
   if (obj->IsSmi()) return i::Smi::cast(*obj)->value() >= 0;
   if (obj->IsNumber()) {
     double value = obj->Number();
+    static const i::DoubleRepresentation minus_zero(-0.0);
+    i::DoubleRepresentation rep(value);
+    if (rep.bits == minus_zero.bits) {
+      return false;
+    }
     return i::FastUI2D(i::FastD2UI(value)) == value;
   }
   return false;

test/cctest/test-api.cc

-// Copyright 2011 the V8 project authors. All rights reserved.
+// Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
@@ -2867,6 +2867,16 @@ THREADED_TEST(isNumberType) {
   obj = env->Global()->Get(v8_str("obj"));
   CHECK(!obj->IsInt32());
   CHECK(!obj->IsUint32());
+  // Positive zero
+  CompileRun("var obj = 0.0;");
+  obj = env->Global()->Get(v8_str("obj"));
+  CHECK(obj->IsInt32());
+  CHECK(obj->IsUint32());
+  // Positive zero
+  CompileRun("var obj = -0.0;");
+  obj = env->Global()->Get(v8_str("obj"));
+  CHECK(!obj->IsInt32());
+  CHECK(!obj->IsUint32());
 }