Bug 446208 - RAP: No visual marker on editable cells.

Fixed the patch-incompatibility introduced with RAP 3.x regarding the
representation of 'GridRow' elements which where changed to be JQuery
objects.

RWT commit:
http://git.eclipse.org/c/rap/org.eclipse.rap.git/commit/?id=0aa425e37f5da5641862f01ae7b8a156f12b873a

Change-Id: I240959cfa56cf76f442a3d59464dd67f53b8f02a
Reviewed-on: https://git.eclipse.org/r/37024
Tested-by: Hudson CI
Reviewed-by: Claudio Guglielmo <claudio.guglielmo@bsiag.com>