Date() should not depend on Date.prototype.toString

Date() should not depend on Date.prototype.toString

We used to call toString as a method which is not safe.

BUG=v8:4225
LOG=Y
R=adamk, littledan
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_chromium_rel_ng;tryserver.blink:linux_blink_rel

Committed: https://crrev.com/6181ec9c2875d380e9abd0d24e386cc7fe2dd28c
Cr-Commit-Position: refs/heads/master@{#29242}

[arv (Not doing code reviews), 2015-06-22 22:25:09]

PTAL

Last one for today

[adamk, 2015-06-22 22:26:19]

lgtm

[arv (Not doing code reviews), 2015-06-23 21:33:07]

The CQ bit was checked by arv@chromium.org

[commit-bot: I haz the power, 2015-06-23 21:33:27]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1200033003/1

[commit-bot: I haz the power, 2015-06-23 21:35:45]

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

[commit-bot: I haz the power, 2015-06-23 21:35:46]

Try jobs failed on following builders:
  v8_presubmit on tryserver.v8 (JOB_FAILED,
http://build.chromium.org/p/tryserver.v8/builders/v8_presubmit/builds/3673)

[arv (Not doing code reviews), 2015-06-23 21:38:41]

git rebase

[arv (Not doing code reviews), 2015-06-23 21:38:54]

The CQ bit was checked by arv@chromium.org

[arv (Not doing code reviews), 2015-06-23 21:38:54]

The patchset sent to the CQ was uploaded after l-g-t-m from adamk@chromium.org
Link to the patchset: https://codereview.chromium.org/1200033003/#ps20001
(title: "git rebase")

[commit-bot: I haz the power, 2015-06-23 21:39:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1200033003/20001

[commit-bot: I haz the power, 2015-06-23 23:18:37]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-06-23 23:18:49]

Patchset 2 (id:??) landed as
https://crrev.com/6181ec9c2875d380e9abd0d24e386cc7fe2dd28c
Cr-Commit-Position: refs/heads/master@{#29242}