Update V8 to version 4.5.1.

Update V8 to version 4.5.1.

Summary of changes available at:
https://chromium.googlesource.com/v8/v8/+log/2e4c5505..ea6801b7

Please follow these instructions for assigning/CC'ing issues:
https://code.google.com/p/v8-wiki/wiki/TriagingIssues

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

[v8-autoroll, 2015-05-17 06:31:34]

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

[commit-bot: I haz the power, 2015-05-17 06:31:45]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1124403007/1

[commit-bot: I haz the power, 2015-05-17 07:45:42]

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

[commit-bot: I haz the power, 2015-05-17 07:45:44]

Try jobs failed on following builders:
  linux_chromium_chromeos_ozone_rel_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)

[Michael Achenbach, 2015-05-17 08:19:15]

The CQ bit was checked by machenbach@chromium.org

[commit-bot: I haz the power, 2015-05-17 08:19:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1124403007/1

[commit-bot: I haz the power, 2015-05-17 09:22:31]

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

[commit-bot: I haz the power, 2015-05-17 09:22:32]

Try jobs failed on following builders:
  linux_chromium_chromeos_ozone_rel_ng on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_...)