Replace the conditions textarea with Ace editor for editing and testing
filter. This uses a soft dependency on CodeEditor; if the latter isn't
installed, the classic textarea is used. The user is still able to
switch between the editors on the go; the new buttons may look a bit
ugly now, but after switching to OOUI they should get much better.
Finally, added a custom syntax highlight for AbuseFilter rules.
Bug: T39192
Change-Id: If3d6a994142e34686bb7fc9f09093f751b599485
Fixed the following rules:
color-hex-length
function-parentheses-space-inside
selector-list-comma-newline-after
Change-Id: Ib30aaeb6179617caa693219d434237e950ef5270
