Misc fixes for window moving and resizing

- Do not skip resizeTask if we're starting or ending drag. We need
  the relayout because surface mode is changing.

- When we're changing the surface mode, need to wait for the first
  draw to finish before we can modify shown frame. Otherwise there
  could be 1 old frame displayed with new position, which makes the
  window position look a bit off.

- Clean up dragResizing/dragResizeChanged flags.

Change-Id: Ia396d6b88fd616ad57aa8cd24ca7e1161add7205