First pass at integrating latest CodeMirror for sprint 36
Fix CSS Context & URL hinting unit test failures.
Remove the redundant check on "(" and rename _isInImportRule to _isInAtRule.
Temporarily disable one HTML code hinting unit test and fix all EditorCommandHandler unit test failures by adjusting third argument of cm.indentLine() call to "true".
Merge pull request #6268 from adobe/nj/cm-sprint36

Integrate latest CodeMirror for sprint 36