Array.prototype.unshift builtin improvements

Array.prototype.unshift builtin improvements

Moving unshift to ElementAccessor and increasing the range of arguments
handled directly in C++, namely directly supporting FastDoubleElementsKind.
This should yield a factor 19 speedup for unshift on fast double arrays.

BUG=

Committed: https://crrev.com/bf6764e6c1197e50ae148755488307a423b1d9b4
Cr-Commit-Position: refs/heads/master@{#30347}

[Camillo Bruni, 2015-08-25 07:13:25]

The CQ bit was checked by cbruni@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-08-25 07:13:29]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1311343002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1311343002/1

[commit-bot: I haz the power, 2015-08-25 07:15:01]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-08-25 07:15:01]

Dry run: Try jobs failed on following builders:
  v8_presubmit on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_presubmit/builds/5177)
  v8_win_compile_dbg on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_win_compile_dbg/builds/6945)

[Camillo Bruni, 2015-08-25 08:29:53]

cbruni@chromium.org changed reviewers:
+ yangguo@chromium.org

[Camillo Bruni, 2015-08-25 08:29:53]

PTAL

[Yang, 2015-08-25 09:04:04]

On 2015/08/25 08:29:53, cbruni wrote:
> PTAL

lgtm.

[Camillo Bruni, 2015-08-25 09:18:24]

The CQ bit was checked by cbruni@chromium.org

[commit-bot: I haz the power, 2015-08-25 09:18:40]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1311343002/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1311343002/40001

[commit-bot: I haz the power, 2015-08-25 09:45:29]

Committed patchset #3 (id:40001)

[commit-bot: I haz the power, 2015-08-25 09:45:48]

Patchset 3 (id:??) landed as
https://crrev.com/bf6764e6c1197e50ae148755488307a423b1d9b4
Cr-Commit-Position: refs/heads/master@{#30347}

[Camillo Bruni, 2015-08-25 11:11:08]

A revert of this CL (patchset #3 id:40001) has been created in
https://codereview.chromium.org/1311363003/ by cbruni@chromium.org.

The reason for reverting is: https://codereview.chromium.org/1315823004/.