DevTools: [CodeMirror] CodeMirror v3.14.1 and new closebrackets plugin

This patch updates closebrackets plugin and codemirror core, which goes
with the plugin as a dependency. This version of codemirror core has
a speed-up patch with lazyfication of measurements to support long lines,
which might be found here:
https://github.com/aslushnikov/CodeMirror/tree/lazy-measure

BUG=

Review URL: https://chromiumcodereview.appspot.com/19168002

git-svn-id: svn://svn.chromium.org/blink/trunk@154231 bbb929c8-8fbe-4397-9dbb-9b2b20218538