Throw IllegalArgumentException when creating bitmaps with invalid dimensions

The real implementation of Bitmap throws an Exception when the target width/height exceeds the source's width/height. The shadows should behave the same.

Could have saved Picasso some troubles: https://github.com/square/picasso/commit/52018980bf7351c0f85150aa71d7401a5c09e595
nit: two-space indent