Include download attribute in list item (#10869)

Clickable list items containing the ng-href attribute currently can't be downloaded on click.

Author: alphatwit

src/components/list/list.js

@@ -406,7 +406,7 @@ function mdListItemDirective($mdAria, $mdConstant, $mdUtil, $timeout) {
       function copyAttributes(source, destination, extraAttrs) {
         var copiedAttrs = $mdUtil.prefixer([
           'ng-if', 'ng-click', 'ng-dblclick', 'aria-label', 'ng-disabled', 'ui-sref',
-          'href', 'ng-href', 'rel', 'target', 'ng-attr-ui-sref', 'ui-sref-opts'
+          'href', 'ng-href', 'rel', 'target', 'ng-attr-ui-sref', 'ui-sref-opts', 'download'
         ]);
 
         if (extraAttrs) {