DevTools: [CodeMirror] roll codemirror to v4.4.1

This rolls codemirror to 2b30a049fd, which is slightly
later than 4.4.1.

Layout test change: In codemirror version 4.4.1 the viewport update logic has changed and it no longer works if text editor offsetHeight is 0px. So creation of editor instance
for tests now setups default editor height of 100px.

R=apavlov
BUG=404120

Review URL: https://codereview.chromium.org/475393002

git-svn-id: svn://svn.chromium.org/blink/trunk@180419 bbb929c8-8fbe-4397-9dbb-9b2b20218538