DevTools: [CodeMirror] roll codemirror presubmit instructions
DevTools: [CodeMirror] roll codemirror presubmit instructions

This patch adds link to CodeMirror roll instructions in the
error message of CodeMirror presubmit check.

R=apavlov, pfeldman

Review URL: https://codereview.chromium.org/352143003

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@176935 bbb929c8-8fbe-4397-9dbb-9b2b20218538

primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs