Fix "missing" vertical grid line on cell deselection

Cell selection color sets "opacity" property, which also affects the
border color. Remove this property if cell is deselected.

Change-Id: I1559373b614f40ef6fd825c16090ad73451a114b
diff --git a/bundles/org.eclipse.rap.rwt/js/rwt/widgets/base/GridRow.js b/bundles/org.eclipse.rap.rwt/js/rwt/widgets/base/GridRow.js
index 49155a2..5175f5c 100644
--- a/bundles/org.eclipse.rap.rwt/js/rwt/widgets/base/GridRow.js
+++ b/bundles/org.eclipse.rap.rwt/js/rwt/widgets/base/GridRow.js
@@ -437,7 +437,10 @@
           "opacity" : ""
         } );
       } else if( this.$cellBackgrounds[ cell ] || this._gridLines.vertical ) {
-        this._getCellBackgroundElement( cell ).css( "backgroundColor", "" );
+        this._getCellBackgroundElement( cell ).css( {
+          "backgroundColor" : "",
+          "opacity" : ""
+        } );
         renderBounds = !this._scrolling;
       }
       if( renderBounds ) {