Bug 898903 - Prevent env["PATH"] from becoming Unicode on Windows. r=jgriffin
Bug 890597 - Transport layer ping diagnostic tool. r=valentin.gosu
Bug 897404 - Port GTK2 to GTK3 - treeview rendering, expander fix. r=karlt
Bug 899460 - Remove MOZ_GTK_EXPANDER. r=karlt
Bug 897185 - toJSON only deals with attributes whose types are serializable. r=bz

Now jsonifiers only include serializable attributes in their returned object, as
per spec.
Backed out changeset e9530cf2baed (bug 890597) for Windows Werror bustage.
bug 899192 fix toolbar button test, r=markh
Bug 899532 - Use whenDelayedStartupFinished() in browser_tab_dragdrop.js; r=gavin
Bug 897396 - Add telemetry to Session Store for restoring a window; r=ttaubert
Merge m-c to fx-team.