Clone crossfilter results before passing on to the chart - highlights…

… data not being updated correctly in BubbleOverlay

spec/bubble-overlay-spec.js

@@ -103,17 +103,17 @@ describe('dc.bubbleOverlay', () => {
         });
     });
 
-    function removeEmptyBins (grp) {
+    function cloneAndRemoveEmptyBins (grp) {
         return {
             all: function () {
-                return grp.all().filter(d => d.value !== 0);
+                return grp.all().map(d => Object.assign({}, d)).filter(d => d.value !== 0);
             }
         };
     }
     describe('filtering another dimension', () => {
         let regionDim;
         beforeEach(() => {
-            chart.group(removeEmptyBins(group)).render();
+            chart.group(cloneAndRemoveEmptyBins(group)).render();
             regionDim = data.dimension(d => d.region);
         });
         function expectRadii (expected) {