Expose SameValue equality comparison algorithm

Expose SameValue equality comparison algorithm

Since SameValue algorithm is defined formally in ECMA262 and V8 already
exported Equals and StrictEquals algorithms, SameValue should be exposed.
And in this issue, we fix the issue of Object::SameValue implementation,
SameValue(0.0, -0.0) returnes true.

BUG=v8:2909
TEST=cctest/test-api/Equality
R=mstarzinger@chromium.org

Committed: http://code.google.com/p/v8/source/detail?r=16924

[yusukesuzuki, 2013-09-24 12:54:43]

V8 issue is here[1].

[1]: https://code.google.com/p/v8/issues/detail?id=2909

[yusukesuzuki, 2013-09-24 12:58:26]

https://chromiumcodereview.appspot.com/24360017/diff/1/src/objects.cc
File src/objects.cc (right):

https://chromiumcodereview.appspot.com/24360017/diff/1/src/objects.cc#newcode...
src/objects.cc:1012: return (this_value != 0) || ((1 / this_value) == (1 /
other_value));
According to the comment of Object::SameValue in objects.h, this method
represents ECMA262 SameValue and Harmony egal operator.
So `SameValue(0.0, -0.0)` should return false.

https://chromiumcodereview.appspot.com/24360017/diff/1/test/cctest/test-api.cc
File test/cctest/test-api.cc (right):

https://chromiumcodereview.appspot.com/24360017/diff/1/test/cctest/test-api.c...
test/cctest/test-api.cc:4976: CHECK(v8_num(0.0)->StrictEquals(v8_num(-0.0)));
Since 0 is int, static_cast<double>(-0) becomes 0.0.

https://chromiumcodereview.appspot.com/24360017/diff/1/test/cctest/test-api.c...
test/cctest/test-api.cc:4992: CHECK(!v8_num(0.0)->SameValue(v8_num(-0.0)));
`SameValue(0.0, -0.0)` becomes false.

https://chromiumcodereview.appspot.com/24360017/diff/1/test/cctest/test-api.c...
test/cctest/test-api.cc:4993: CHECK(not_a_number->SameValue(not_a_number));
`SameValue(NaN, NaN)` becomes true.

[Michael Starzinger, 2013-09-24 16:32:45]

LGTM. I'll land this.

[Michael Starzinger, 2013-09-24 16:51:53]

Committed patchset #1 manually as r16924 (presubmit successful).