Fix flash caused by frame resize code

This fixes a problem where the frame would resize mid-animation because
the widget frame was being always being resized.

The issue was caused by having an extra fadeOutChallenge() in
onPageSwitching().   The fix is to remove this and handle this case
special for warping in onPageEndWarp()

Fixes bug 11190745

Change-Id: I6dbda4d09c77e3923887f8d41efb2215e1afb1b9