mw.ViewPageTarget: Fix broken firstHeading transition

Class ve-init-mw-viewPageTarget-pageTitle added various
transition settings that were never used. Meanwhile, we're doing
fadeTo which sets inline opacity css every X ms until the
animation is finished.

* Changed the inline jQuery animation  to use css transitions
  instead.
* Removed the inexistent and obsolete ms-transition declaration.
* Removed ":visible" from selector query. This makes the selector
  more performant (since :visible is a proprietary Sizzle keyword)
  and it was obsolete anyway. The classes don't affect display none/hide,
  this is handled naturally by the browser now.

Change-Id: Ibdfb442ff6c743ef16b514a7696796ee27821887
Merge "mw.ViewPageTarget: Fix broken firstHeading transition"