Post/page editing box does not need resize handle anymore

[senff]

With 4.0 and the way it handles the height and position of the editing area for posts and pages, the resize handle on the bottom right corner of the editor is not needed anymore. Currently set to display:none but for cleanup purposes and avoid future bloat, it can be removed altogether.

[ocean90]

It's still possible to use the editor without the expanding feature, see Screen Options for example.