Bug 1318339 - [DateTimeInput] Prevent reset button from getting focus. r=mossop

Reset button should not be tabbable or focusable.

MozReview-Commit-ID: IboMKl3n0LY

toolkit/content/widgets/datetimebox.xml

@@ -1157,7 +1157,7 @@
       <property name="EVENTS" readonly="true">
         <getter>
         <![CDATA[
-          return ["click", "focus", "blur", "copy", "cut", "paste"];
+          return ["click", "focus", "blur", "copy", "cut", "paste", "mousedown"];
         ]]>
         </getter>
       </property>
@@ -1552,6 +1552,12 @@
               this.onBlur(aEvent);
               break;
             }
+            case "mousedown": {
+              if (aEvent.originalTarget == this.mResetButton) {
+                aEvent.preventDefault();
+              }
+              break;
+            }
             case "copy":
             case "cut":
             case "paste": {