Backed out changeset ec7bccd33fc0 (bug 846340) for frequent failures.
CLOSED TREE
Backed out 3 changesets (bug 883358) for Android mochitest-3 failures on a CLOSED TREE.

Backed out changeset 84b35dd1879d (bug 883358)
Backed out changeset b5e6522257cb (bug 883358)
Backed out changeset 757a3f2e5de6 (bug 883358)
bug 837293. Don't send keyPress events for characters that were pressed at the same time as the altGr button. When our CharacterReceived handler fires, don't send modifier key information if it includes the altGr button. r=bbondy
bug 879382. Remove support for windowless plugin input from metro widget. r=jimm
bug 873542 - Remove ENABLE_MARIONETTE from debug FF configs, r=dburns