Bug 1038534 - Don't let ProGuard discard (support) Fragments. r=nalexander

The presenting Fragments are those of the Search Activity; but in
general, Fragments are referred to by class at runtime, so they must be
preserved.  The ProGuard system is not aware of Fragments referenced
only in XML files, so we need to keep them around manually.
Bug 1029292 - Replace Search Activity's GeckoView with WebView. r=nalexander
Bug 1037374 - Uplift Add-on SDK to Firefox r=me
bug 1037488 - MediaEngineTabVideoSource should set width, height and framerate based on constraints and prefs passed to Allocate() r=jesup
bug 1037644 - don't use mozAfterPaint events to drive tab stream r=jesup
Bug 1038227 - Record search history in Fennec. r=rnewman
Bug 1027135 - Only touch PageActionLayout on UI thread. r=wesj
Bug 1027137 - PageActionLayout cleanup. r=wesj
Bug 1021356 - Part 2: Empty private tabs panel visual refinements for tablet. r=lucasr
Merge fx-team to m-c a=merge