Making dynamic height resize like in TextFormField

[Dariusz-Pluta]

When u set maxLines = null in TextFormField it dynamically resize to show whole input text, here u can't do that, and text is being cropped if it's too long :)

[hslbetto]

The param maxLines change the number of lines the field will show content. By default it is 1 and can't be seted as null.
However, if you set a value bigger than 1, it'll work fine and show the content that fit into this space.