wym.js: improved getSelectedContainer (now uses contentWindow.getSelection()).
wym.js: improved getSelectedContainer (now uses contentWindow.getSelection()).

samuelcole/wymeditor,mrlundis/wymeditor-legacy,samuelcole/wymeditor,samuelcole/wymeditor,mrlundis/wymeditor-legacy,mrlundis/wymeditor-legacy,samuelcole/wymeditor,mrlundis/wymeditor-legacy,samuelcole/wymeditor,samuelcole/wymeditor