fix(ui-grid-render-container): Use offsetHeight to avoid sizing issues.

Also, revert 76e18d6.

fix #6480

Author: cybermerlin

src/js/core/directives/ui-grid-render-container.js

@@ -157,7 +157,15 @@
               ret += '\n .grid' + uiGridCtrl.grid.id + ' .ui-grid-render-container-' + $scope.containerId + ' .ui-grid-header-canvas { width: ' + (canvasWidth + grid.scrollbarWidth) + 'px; }';
 
               if (renderContainer.explicitHeaderCanvasHeight) {
-                ret += '\n .grid' + uiGridCtrl.grid.id + ' .ui-grid-render-container-' + $scope.containerId + ' .ui-grid-header-canvas { height: ' + renderContainer.explicitHeaderCanvasHeight + 'px; }';
+                // get height from body container
+                var reHCHeight = document.querySelector('.grid'+uiGridCtrl.grid.id+' .ui-grid-render-container-body .ui-grid-header-canvas');
+
+                if (reHCHeight) {
+                  renderContainer.explicitHeaderCanvasHeight = reHCHeight.offsetHeight;
+                }
+
+                ret += '\n .grid' + uiGridCtrl.grid.id + ' .ui-grid-render-container-' + $scope.containerId +
+                  ' .ui-grid-header-canvas { height: ' + renderContainer.explicitHeaderCanvasHeight + 'px; }';
               }
               else {
                 ret += '\n .grid' + uiGridCtrl.grid.id + ' .ui-grid-render-container-' + $scope.containerId + ' .ui-grid-header-canvas { height: inherit; }';

src/js/core/factories/Grid.js

@@ -2159,8 +2159,8 @@ angular.module('ui.grid')
         }
 
         if (container.header || container.headerCanvas) {
-          container.explicitHeaderHeight = null;
-          container.explicitHeaderCanvasHeight = null;
+          container.explicitHeaderHeight = container.explicitHeaderHeight || null;
+          container.explicitHeaderCanvasHeight = container.explicitHeaderCanvasHeight || null;
 
           containerHeadersToRecalc.push(container);
         }