DevTools: improve javascript formatter to support "return" properties.

DevTools: improve javascript formatter to support "return" properties.

The uglifier tokenizer, which is used under the hood in javascript
formatter, is not clever enough to figure out that the "return" word
in "a.return" is not a "return" statement, but identifier.
This patch works around this issue via verifying the token value after
regex to be a valid identifier.

BUG=218470
R=vsevik, apavlov

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=180467

[vsevik, 2014-08-18 09:33:53]

The CQ bit was checked by vsevik@chromium.org

[vsevik, 2014-08-18 09:33:53]

lgtm

[commit-bot: I haz the power, 2014-08-18 09:34:44]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/lushnikov@chromium.org/479033002/20001

[commit-bot: I haz the power, 2014-08-18 10:36:01]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  linux_blink_dbg on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/linux_blink_dbg/builds/2...)
  linux_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/linux_blink_rel/builds/2...)
  mac_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/mac_blink_rel/builds/20166)
  win_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/win_blink_rel/builds/23183)

[commit-bot: I haz the power, 2014-08-18 11:02:26]

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

[commit-bot: I haz the power, 2014-08-18 11:02:27]

Try jobs failed on following builders:
  linux_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/linux_blink_rel/builds/2...)

[lushnikov, 2014-08-18 14:34:45]

The CQ bit was checked by lushnikov@chromium.org

[commit-bot: I haz the power, 2014-08-18 14:35:37]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/lushnikov@chromium.org/479033002/20001

[commit-bot: I haz the power, 2014-08-18 15:33:01]

Committed patchset #2 (20001) as 180467