DevTools: roll CodeMirror to v4.0.3

This patch rolls codemirror to version 4.0.3.
It also rolls all supporting plugins we use, though leaving highlighting
modes intact.

BUG=356878

Review URL: https://codereview.chromium.org/216973004

git-svn-id: svn://svn.chromium.org/blink/trunk@170462 bbb929c8-8fbe-4397-9dbb-9b2b20218538