fix(uiGridUtil): getBorderSize() missing "width"

The correct property name to use is "borderWidth", not just "border".
"border" works in Chrome but was breaking in Firefox.

Also had to change .ui-grid-header's box-sizing to content-box so IE11
would include the border in height calcs. AND finally IE11 was returning
fractional heights so Grid parseInt()s the returned values.

src/js/core/factories/Grid.js

@@ -1525,7 +1525,7 @@ angular.module('ui.grid')
             var oldHeaderHeight = container.headerHeight;
             var headerHeight = gridUtil.outerElementHeight(container.header);
 
-            container.headerHeight = headerHeight;
+            container.headerHeight = parseInt(headerHeight, 10);
 
             if (oldHeaderHeight !== headerHeight) {
               rebuildStyles = true;
@@ -1534,7 +1534,9 @@ angular.module('ui.grid')
             // Get the "inner" header height, that is the height minus the top and bottom borders, if present. We'll use it to make sure all the headers have a consistent height
             var topBorder = gridUtil.getBorderSize(container.header, 'top');
             var bottomBorder = gridUtil.getBorderSize(container.header, 'bottom');
-            var innerHeaderHeight = headerHeight - topBorder - bottomBorder;
+            var innerHeaderHeight = parseInt(headerHeight - topBorder - bottomBorder, 10);
+
+            innerHeaderHeight  = innerHeaderHeight < 0 ? 0 : innerHeaderHeight;
 
             container.innerHeaderHeight = innerHeaderHeight;
 

src/js/core/services/ui-grid-util.js

@@ -757,6 +757,8 @@ module.service('gridUtil', ['$log', '$window', '$document', '$http', '$templateC
       borderType = 'border';
     }
 
+    borderType += 'Width';
+
     var val = parseInt(styles[borderType], 10);
 
     if (isNaN(val)) {

src/less/header.less

@@ -7,6 +7,7 @@
 
 .ui-grid-header {
   border-bottom: 1px solid @borderColor;
+  box-sizing: content-box;;
 }
 
 .ui-grid-top-panel {