fix(Filtering): Redraw grid properly when scrolled

The grid was not setting the row offset properly when removing a filter
when the grid was scrolled. This change adds a "rowsAltered" argument to
Grid.refresh() which will then pass that argument to Grid.redrawInPlace()
so the grid can be refreshed at the proper place.

Fixes #2557

Author: c0bra

src/js/core/directives/ui-grid-header-cell.js

@@ -242,14 +242,7 @@
                 filterDeregisters.push($scope.$watch('col.filters[' + i + '].term', function(n, o) {
                   if (n !== o) {
                     uiGridCtrl.grid.api.core.raise.filterChanged();
-                    uiGridCtrl.grid.refresh()
-                      .then(function () {
-                        if (uiGridCtrl.prevScrollArgs && uiGridCtrl.prevScrollArgs.y && uiGridCtrl.prevScrollArgs.y.percentage) {
-                          var scrollEvent = new ScrollEvent(uiGridCtrl.grid,null,null,'uiGridHeaderCell.toggleMenu');
-                          scrollEvent.y.percentage = uiGridCtrl.prevScrollArgs.y.percentage;
-                          scrollEvent.fireScrollingEvent();
-                        }
-                      });
+                    uiGridCtrl.grid.refresh(true);
                   }
                 }));  
               });

src/js/core/factories/Grid.js

@@ -1809,11 +1809,9 @@ angular.module('ui.grid')
    * @name refresh
    * @methodOf ui.grid.class:Grid
    * @description Refresh the rendered grid on screen.
-   * 
+   * @params {boolean} [rowsAltered] Optional flag for refreshing when the number of rows has changed.
    */
-  Grid.prototype.refresh = function refresh() {
-    // gridUtil.logDebug('grid refresh');
-    
+  Grid.prototype.refresh = function refresh(rowsAltered) {
     var self = this;
 
     var p1 = self.processRowsProcessors(self.rows).then(function (renderableRows) {
@@ -1825,11 +1823,11 @@ angular.module('ui.grid')
     });
 
     return $q.all([p1, p2]).then(function () {
-      self.redrawInPlace();
+      self.redrawInPlace(rowsAltered);
 
       self.refreshCanvas(true);
     });
-  };  
+  };
 
   /**
    * @ngdoc function