seemingly wrong brush selector

that often worked
thanks @paulbriton for tracking this down!
this seems to be a mistake introduced in 354b890
fixes #1134

src/coordinate-grid-mixin.js

@@ -1009,7 +1009,7 @@ dc.coordinateGridMixin = function (_chart) {
     };
 
     _chart.setBrushY = function (gBrush) {
-        gBrush.selectAll('.brush rect')
+        gBrush.selectAll('rect')
             .attr('height', brushHeight());
         gBrush.selectAll('.resize path')
             .attr('d', _chart.resizeHandlePath);