Disable animation when adjusting font size.

- The fade-in and fade-out animation for transitioning between
different frames in the text preview is very janky. Disable the
animation to get a smoother transition while dragging along the seek
bar.

Change-Id: I201faf8229961ea5fa5fe42efd312290a4af0f30
Fixes: 71569578
Test: visual

src/com/android/settings/PreviewSeekBarPreferenceFragment.java

@@ -67,7 +67,7 @@ public abstract class PreviewSeekBarPreferenceFragment extends SettingsPreferenc
 
         @Override
         public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
-            setPreviewLayer(progress, true);
+            setPreviewLayer(progress, false);
             if (!mSeekByTouch) {
                 commit();
             }