FlingTracker can divide by zero and hang StatusBar in an infinite loop

if 2 events have the same timestamp then FlingTracker in PanelView will divide
by zero causing NaNs. the bug is usually triggered by rapid StatusBar up/down
dragging activity and updateCarrierLabelVisibility can then loop indefinitely
looking at NaNs. the user visible symptom is that StatusBar refuses to pull
down and is burning cpu time.

Signed-off-by: Michael Bestas <mikeioannina@gmail.com>

Change-Id: I0791c6bea953bf03346185fc6aaf44aaea79aace
IME : Fix sym key regression

http://review.cyanogenmod.org/#/c/25787/2 caused the "dismiss" arrow
for ime's to execute back action as well. Reproducible via :

Open sms app->Open message thread->Tap message field->Tap downward arrow on navbar

Expected behaviour : Keyboard should be dismissed
Actual behaviour : Keyboard is dismissed and user is taken to previous screen.

Change-Id: I6ab65b00464fb6e00849d7fd6c8bd438b23ee76b
Fix divisions by zero on boot.

Change I976ffae3a56d411b00026f86b16efa9743a23293 introduced a problem
where depending on the rotation settings the WM override display
configuration would be filled with invalid values.
Fix that by correctly checking that the display is ready prior to
setting the override configuration.

Change-Id: Ia3fd7603d9c1212cd32536803b4c12390a798606

Conflicts:

	services/java/com/android/server/wm/WindowManagerService.java