Fixed input context trying to squeeze content into a full widget.

Fixed input context trying to squeeze content into a full widget.

Problem was reproduced on N97. If the FEP detects that the widget is
full while still editing text, it will try to send those events as
key events instead. Since this screws up the content in the widget,
we stop those events from reaching the widget in the input context.

AutoTest: Passed
Task:     QTBUG-12949
RevBy:    Miikka Heikkinen
(cherry picked from commit 5ca6264933af60b3cd376b7f08bea008fa69b515)