Remove overrides in BlinkPlatformImpl.

Remove overrides in BlinkPlatformImpl.

We don't use override annotations for the Blink API. These seem to
have sneaked in.

BUG=

Committed: https://crrev.com/0b7b27587319dbc86e363501eb83ea99f39f10df
Cr-Commit-Position: refs/heads/master@{#301285}

[Peter Beverloo, 2014-10-24 13:42:09]

peter@chromium.org changed reviewers:
+ jam@chromium.org, mkwst@chromium.org

[Peter Beverloo, 2014-10-24 13:42:09]

jam: PTAL (removing 11 overrides).
mkwst: FYI

[Mike West, 2014-10-24 13:42:43]

LGTM, thanks.

[jam, 2014-10-24 23:40:05]

lgtm

[Peter Beverloo, 2014-10-25 13:47:12]

The CQ bit was checked by peter@chromium.org

[commit-bot: I haz the power, 2014-10-25 13:47:36]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/679523004/1

[commit-bot: I haz the power, 2014-10-25 14:40:02]

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

[commit-bot: I haz the power, 2014-10-25 14:40:04]

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

[Peter Beverloo, 2014-10-25 15:39:59]

The CQ bit was checked by peter@chromium.org

[commit-bot: I haz the power, 2014-10-25 15:40:37]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/679523004/1

[commit-bot: I haz the power, 2014-10-25 16:09:46]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-10-25 16:10:22]

Patchset 1 (id:??) landed as
https://crrev.com/0b7b27587319dbc86e363501eb83ea99f39f10df
Cr-Commit-Position: refs/heads/master@{#301285}