Remove --enable-region-based-columns command line flag.

Remove --enable-region-based-columns command line flag.

Region based columns (aka. the new multicol implementation) now gets enabled
via an entry in RunTimeEnabledFeatures in Blink.

BUG=350853
R=jochen@chromium.org,mkwst@chromium.org

Committed: https://crrev.com/cf3c13e6562ee31f777944bae2461bac87d6ca9f
Cr-Commit-Position: refs/heads/master@{#331767}

[jochen (gone - plz use gerrit), 2015-05-27 14:58:14]

lgtm

[mstensho (USE GERRIT), 2015-05-27 15:36:41]

The CQ bit was checked by mstensho@opera.com

[commit-bot: I haz the power, 2015-05-27 15:37:30]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1150663003/1

[commit-bot: I haz the power, 2015-05-27 15:44:49]

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

[commit-bot: I haz the power, 2015-05-27 15:44:50]

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

[mstensho (USE GERRIT), 2015-05-27 16:13:21]

mstensho@opera.com changed reviewers:
+ mkwst@chromium.org

[mstensho (USE GERRIT), 2015-05-27 16:14:04]

Thanks. Looks like I need moar l-g-t-m, though. Adding mkwst.

[Mike West, 2015-05-28 06:17:43]

Dropping the member from IPC LGTM.

[mstensho (USE GERRIT), 2015-05-28 10:49:30]

The CQ bit was checked by mstensho@opera.com

[commit-bot: I haz the power, 2015-05-28 10:49:39]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1150663003/1

[commit-bot: I haz the power, 2015-05-28 12:06:11]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-05-28 12:06:57]

Patchset 1 (id:??) landed as
https://crrev.com/cf3c13e6562ee31f777944bae2461bac87d6ca9f
Cr-Commit-Position: refs/heads/master@{#331767}