Migrate 'wgBreakFrames' from wikibits.js to mediawiki.page.ready

This module now contains the same code as in wikibits.js.

For cached entries the new code works automatically since both
legacy wikibits and mediawiki.page.ready are already present in
the load() queue of existing pages.

Change-Id: I18b068fbcf4ba0646fb07313c3d9676cc76a0ad5
Merge "Migrate 'wgBreakFrames' from wikibits.js to mediawiki.page.ready"