I've run all unit tests without errors and also Smoke Tests, where 3 steps failed (2 (Multi Browser) Live Preview, 1 Inline Editor), but they also fail on master. I'll see whether they are already filed and file them if not.
CodeMirror releases page
Fix CSS Parsing unit tests
They failed due to these two commits: codemirror/CodeMirror@2dd1762...26ec5f3
Force "textarea" mode
Fix for the change in CodeMirror commit.