Fix crash in AnimationDrawable

When a drawable becomes invisible, it unschedule itself, which
sets mCurrentFrame to -1. Later, when it becomes visible, it
calls setFrame() with either 0 (if 'restart' is true) or
mCurrentFrame. Calling setFrame() with a value of -1 causes a crash
later as we dereference an invalid location in the state durations
array.

This fix also checks mCurrentFrame and calls setFrame with 0 when the
current frame is invalid. This takes the code back closer to what it
used to be when setFrame was always called with 0, although now it will
use a valid frame when it is set.

Issue #16489419 Google Translate crashes whenever hitting done button on keyboard to get translation result.

Change-Id: I1f5b8672d209017aa8a4eaa15bd7ddd2f3ae38d1