Update V8 to version 5.2.20.

Update V8 to version 5.2.20.

Summary of changes available at:
https://chromium.googlesource.com/v8/v8/+log/f7a11412..d8d54ea9

Please follow these instructions for assigning/CC'ing issues:
https://github.com/v8/v8/wiki/Triaging%20issues

Please close rolling in case of a roll revert:
https://v8-roll.appspot.com/
This only works with a Google account.

TBR=hablich@chromium.org,machenbach@chromium.org,yangguo@chromium.org,vogelheim@chromium.org

Committed: https://crrev.com/31e492eab1deee4798c016ed4d7b306997f4dd82
Cr-Commit-Position: refs/heads/master@{#386958}

[v8-autoroll, 2016-04-13 07:32:18]

The CQ bit was checked by v8-autoroll@chromium.org

[commit-bot: I haz the power, 2016-04-13 07:32:31]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1884913002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1884913002/1

[commit-bot: I haz the power, 2016-04-13 08:50:00]

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

[commit-bot: I haz the power, 2016-04-13 08:50:01]

Try jobs failed on following builders:
  linux_android_rel_ng on tryserver.chromium.android (JOB_FAILED,
https://build.chromium.org/p/tryserver.chromium.android/builders/linux_androi...)

[v8-autoroll, 2016-04-13 09:00:25]

The CQ bit was checked by v8-autoroll@chromium.org

[commit-bot: I haz the power, 2016-04-13 09:00:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1884913002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1884913002/1

[commit-bot: I haz the power, 2016-04-13 10:15:44]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-04-13 10:17:36]

Description was changed from

==========
Update V8 to version 5.2.20.

Summary of changes available at:
https://chromium.googlesource.com/v8/v8/+log/f7a11412..d8d54ea9

Please follow these instructions for assigning/CC'ing issues:
https://github.com/v8/v8/wiki/Triaging%20issues

Please close rolling in case of a roll revert:
https://v8-roll.appspot.com/
This only works with a Google account.

TBR=hablich@chromium.org,machenbach@chromium.org,yangguo@chromium.org,vogelhe...
==========

to

==========
Update V8 to version 5.2.20.

Summary of changes available at:
https://chromium.googlesource.com/v8/v8/+log/f7a11412..d8d54ea9

Please follow these instructions for assigning/CC'ing issues:
https://github.com/v8/v8/wiki/Triaging%20issues

Please close rolling in case of a roll revert:
https://v8-roll.appspot.com/
This only works with a Google account.

TBR=hablich@chromium.org,machenbach@chromium.org,yangguo@chromium.org,vogelhe...

Committed: https://crrev.com/31e492eab1deee4798c016ed4d7b306997f4dd82
Cr-Commit-Position: refs/heads/master@{#386958}
==========

[commit-bot: I haz the power, 2016-04-13 10:17:37]

Patchset 1 (id:??) landed as
https://crrev.com/31e492eab1deee4798c016ed4d7b306997f4dd82
Cr-Commit-Position: refs/heads/master@{#386958}

[Nico, 2016-04-13 11:43:26]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1877403004/ by thakis@chromium.org.

The reason for reverting is:
https://build.chromium.org/p/chromium.fyi/builders/WinClang/builds/205/steps/...

../../v8/src/runtime/runtime-atomics.cc(126,1):  error: unused function
'LoadSeqCst' [-Werror,-Wunused-function]
ATOMIC_OPS(int8_t, 8, char)
^
../../v8/src/runtime/runtime-atomics.cc(120,15):  note: expanded from macro
'ATOMIC_OPS'
  inline type LoadSeqCst(type* p) { return *p; }                            \
              ^.