Initialize FastBitmapDrawable bounds with default bitmap dimensions.

Change-Id: Ida9603e35b242a581b9401c6440875cd511725a1

src/com/android/launcher3/FastBitmapDrawable.java

@@ -32,6 +32,7 @@ class FastBitmapDrawable extends Drawable {
     FastBitmapDrawable(Bitmap b) {
         mAlpha = 255;
         mBitmap = b;
+        setBounds(0, 0, b.getWidth(), b.getHeight());
     }
 
     @Override