Revert of DevTools: Roll CodeMirror to 5.25.1

Revert of DevTools: Roll CodeMirror to 5.25.1 (patchset #2 id:20001 of https://codereview.chromium.org/2772343006/ )

Reason for revert:
Poor performance on long bidi lines.

Original issue's description:
> DevTools: Roll CodeMirror to 5.25.1
> 
> This mainly to fix bugs where line numbers appear outside the gutter.
> This patch also removes the SimpleMode since it was never used.
> 
> BUG=none
> R=lushnikov@chromium.org
> 
> Review-Url: https://codereview.chromium.org/2772343006 .
> Cr-Commit-Position: refs/heads/master@{#460469}
> Committed: https://chromium.googlesource.com/chromium/src/+/02128266dda94d175c6e4070a7f67b6232d6ae03

TBR=lushnikov@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=none

[einbinder, 2017-05-04 01:08:13]

The CQ bit was checked by einbinder@chromium.org

[einbinder, 2017-05-04 01:08:14]

Created Revert of DevTools: Roll CodeMirror to 5.25.1

[commit-bot: I haz the power, 2017-05-04 01:08:43]

CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-05-04 02:23:45]

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

[commit-bot: I haz the power, 2017-05-04 02:23:46]

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

[lushnikov, 2017-05-04 20:32:22]

Let's annotate this with a proper BUG number.
Also, it looks like more changes are required since trybots failed