trimmed stable release 31.0.1650.63
Merge remote-tracking branch 'origin/bugfix/removeSpellingMarker/30.0.1599.101' into bugfix/removeSpellingMarker/31.0.1650.63
Fix compile errors for v31

* Frame::editor() now returns reference instead of pointer
  (https://chromiumcodereview.appspot.com/23518002)
* Node::document() now returns reference instead of pointer
  (https://codereview.chromium.org/23819007)