ENYO-3743: show css button when enabled for the first time...

... this fixes a small bug where the hera editor button is not shown even
if the feature is enabled. This bug occurred only when the editor is enabled
right after opening the first css file.
Fix is so Hera stay open between tab switches

Enyo-DCO-1.1-Signed-off-by: johnmcconnell@yahoo.com