[Mobile] wrong cursor with external keyboard

[aleripe]

My issue is about [Mobile]

I have tried running example directory successfully before creating an issue here. Latest Flutter version in stable channel.

Sony Xperia Tablet with Android 5.1.1 and a bluetooth external keyboard. Running the examplate directory. I type some text then press backspace some times. When I try to insert some other text cursor position is wrong, usually a random number of characters after.

[singerdmx]

Please submit a PR to fix it