Upgraded to WP 3.9 and everything is working fine except an old bug reported in WP 3.5 is back.
When I create a new post the editor text area is ~9 pages in height with no scroll bar. BTW - the post editor width is fine. If I manually drag the editor window control in the lower right corner to reduce the number of lines in the window, it doesn't save the new window size after saving... the post editor is back to a huge vertical size.
Created a new post results in a huge editor text area:
After manually resizing to the editor area to about 1 screen in height - the editor scroll bar now showing:
Obviously the editor size numbers are invalid.
Same issue when editing posts Chrome 34.0.1847.116 m.
Let me know if you need more debug info.