Bug 1236325 - Annotate intentional switch fallthrough to suppress -Wimplicit-fallthrough warning in satchel. r=mak

toolkit/components/satchel/nsFormFillController.cpp:974:3 [-Wimplicit-fallthrough] unannotated fall-through between switch labels

toolkit/components/satchel/nsFormFillController.cpp

@@ -961,7 +961,7 @@ nsFormFillController::KeyPress(nsIDOMEvent* aEvent)
       if (isCtrl || isAlt || isMeta)
         break;
     }
-    /* fall through */
+    MOZ_FALLTHROUGH;
   case nsIDOMKeyEvent::DOM_VK_UP:
   case nsIDOMKeyEvent::DOM_VK_DOWN:
   case nsIDOMKeyEvent::DOM_VK_LEFT: