Restore basic styling to toolbar in core target (only)

Most document editors expose B/I in the toolbar. Hiding
B/I was a MediaWiki-specific feature request (or even WMF
sepcific) and the MW target file already specifies that behaviour.

Change-Id: I697b3f47cac225142346c8a31c50c7dd5e8b2609
Merge "Restore basic styling to toolbar in core target (only)"