bug with transform() function

[EscapedGibbon]

If the transform function uses 2x3 matrix instead of 3x3 and puts fullImage:true in options, transformation will throw an error.
The reason is that with fullImage we calculate new corners of the image with modified transformPoint function, where we use 3x3 matrix instead of 2x3. And right now, if 2x3 matrix is passed in parameters, when calculating fullImage corners, last matrix row is yet undefined, which provokes an error. It's an easy fix, just need to put the matrix size check before calculating.