[turbofan] Use CompareNilIC for abstract equality with null/undefined.

[turbofan] Use CompareNilIC for abstract equality with null/undefined.

Change CompareNilIC to return true/false instead of 1/0, and use the
CompareNilICStub in TurboFan for abstract equality with null/undefined.
This way we don't always run into the %Equals runtime fallback when
comparing objects with null/undefined.

R=jarin@chromium.org

Committed: https://crrev.com/c9ab36061d26e4f79d50793c6dcbeb4256b76401
Cr-Commit-Position: refs/heads/master@{#31596}

[Benedikt Meurer, 2015-10-27 10:47:49]

Hey Jaro,

Here's an implementation of danno's short-term suggestion to use the
CompareNilIC, which gives us some performance back on Richards without wasting
too much time on something we don't want to keep long-term.
Please take a look.

Thanks,
Benedikt

[Jarin, 2015-10-27 11:00:00]

lgtm.

https://codereview.chromium.org/1417503008/diff/1/src/compiler/js-typed-lower...
File src/compiler/js-typed-lowering.cc (right):

https://codereview.chromium.org/1417503008/diff/1/src/compiler/js-typed-lower...
src/compiler/js-typed-lowering.cc:623: value->ReplaceInput(0, node);
This whole input/use massaging business is really terrible.

[Benedikt Meurer, 2015-10-27 11:19:42]

The CQ bit was checked by bmeurer@chromium.org

[commit-bot: I haz the power, 2015-10-27 11:19:54]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1417503008/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1417503008/1

[commit-bot: I haz the power, 2015-10-27 11:21:30]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-27 11:21:53]

Patchset 1 (id:??) landed as
https://crrev.com/c9ab36061d26e4f79d50793c6dcbeb4256b76401
Cr-Commit-Position: refs/heads/master@{#31596}