[turbofan] Add support for inlining of builtins.

[turbofan] Add support for inlining of builtins.

We mark certain builtins for inlining, and those should always be
inlined into optimized code (CrankShaft already handles it this way), so
we should support that in TurboFan as well. Currently this mainly
affects a certain set of Math functions, but once have the basics in
place we can extend this to any kind of builtin/code stub/accessor.

This adds a new flag --turbo_builtin_inlining (enabled by default), that
forces the inliner to always inline builtins marked for inlining, but
does not affect inlining of other functions (this is still controlled by
the --turbo-inlining flag).

BUG=v8:3952
LOG=n
R=jarin@chromium.org

Committed: https://crrev.com/25895aeeaf79918ebf9eecf1535e7a8e5bed9e97
Cr-Commit-Position: refs/heads/master@{#27059}

[Benedikt Meurer, 2015-03-09 07:58:39]

Michi: FYI

[Jarin, 2015-03-09 08:03:57]

looks good to me, but Michi might want to have a look at the massaging of flags.

[Jarin, 2015-03-09 08:04:23]

On 2015/03/09 08:03:57, jarin wrote:
> looks good to me, but Michi might want to have a look at the massaging of
flags.

lgtm.

[commit-bot: I haz the power, 2015-03-09 08:05:52]

Patchset 1 (id:??) landed as
https://crrev.com/25895aeeaf79918ebf9eecf1535e7a8e5bed9e97
Cr-Commit-Position: refs/heads/master@{#27059}

[Benedikt Meurer, 2015-03-09 08:05:53]

Committed patchset #1 (id:1) manually as
25895aeeaf79918ebf9eecf1535e7a8e5bed9e97 (presubmit successful).