Add left padding to CodeMirror when line numbers are hidden.
Fix text selection problem
Assign the show-line-padding class to editor holder by default
Fix initilization of editor holder line padding
Create Editor._toggleLinePadding() and small code clean up
Add darker background color to padding when line numbers are hidden
Fix inline editor background styles
Small style clean up
Change .inline-text-editor styles to nested .CodeMirror styles
Merge pull request #7641 from lkcampbell/fix-7283

Fix Issue #7283: Padding with line numbers turned off is broken