Use css height:auto to layout inline editors, cmv3 wrapper element for inline editor height.

Alternate fix for porting ``totalHeight()`` into cmv3 branch. 

@njx I just found your notes here https://github.com/adobe/brackets/wiki/CodeMirror-v3-integration. I didn't see any issues in full or inline editors when letting CodeMirror lay itself out with the provided ``height:auto`` change. The only other thing the original ``totalHeight`` does is account for the height of inline editors which we don't have a use case for. Either (a) nested inline editors and getting the outermost total height or (b) getting the height of a full editor that contains inline editor.

See adobe/CodeMirror2#80 for the proposed cmv3 patch.