Attached is the fix. It is again related to changed made for RM3294, the font size was set to 0em. Also included changes to make sure CodeMirror font size is never set to 0em but to default 1em if font size is not available from preferences.
Unfortunately this fails linting, and when that is fixed, fails the tests:
HeadlessChrome 0.0.0 (Mac OS X 10.12.6) SqlEditorUtils Calculate font size of input number passed calcFontSize FAILED
Expected '1em' to equal '0em'.
at UserContext.<anonymous> (regression/javascript/webpack:/regression/javascript/sqleditor_utils_spec.js:35:47)
HeadlessChrome 0.0.0 (Mac OS X 10.12.6): Executed 660 of 741 (1 FAILED) (0 secs / 7.075 secs)
HeadlessChrome 0.0.0 (Mac OS X 10.12.6) SqlEditorUtils Calculate font size of input number passed calcFontSize FAILED
Expected '1em' to equal '0em'.
HeadlessChrome 0.0.0 (Mac OS X 10.12.6): Executed 741 of 741 (1 FAILED) (7.74 secs / 7.383 secs)