Bug 1348052 - Change the scroll buttons in the datetime picker to move the view, not the list. r=mconley

MozReview-Commit-ID: EfgDEg6jY7F

--HG--
extra : rebase_source : db35c38213c04ef2b5a0ebcefe9b67de90b70bb8

toolkit/content/widgets/spinner.js

@@ -300,11 +300,11 @@ function Spinner(props, context) {
             // An "active" class is needed to simulate :active pseudo-class
             // because element is not focused.
             event.target.classList.add("active");
-            this._smoothScrollToIndex(index + 1);
+            this._smoothScrollToIndex(index - 1);
           }
           if (event.target == down) {
             event.target.classList.add("active");
-            this._smoothScrollToIndex(index - 1);
+            this._smoothScrollToIndex(index + 1);
           }
           if (event.target.parentNode == spinner) {
             // Listen to dragging events