Bug 830405 - Make Clear Downloads button "tabbable" on Mac.

r=Mano

browser/components/places/content/downloadsViewOverlay.xul

@@ -35,6 +35,9 @@
 
   <toolbar id="placesToolbar">
     <toolbarbutton id="clearDownloadsButton"
+#ifdef XP_MACOSX
+                   class="tabbable"
+#endif
                    insertbefore="libraryToolbarSpacer"
                    label="&clearDownloadsButton.label;"
                    command="downloadsCmd_clearDownloads"

browser/components/places/jar.mn

@@ -31,4 +31,4 @@ browser.jar:
     content/browser/places/moveBookmarks.js              (content/moveBookmarks.js)
     content/browser/places/editBookmarkOverlay.xul       (content/editBookmarkOverlay.xul)
     content/browser/places/editBookmarkOverlay.js        (content/editBookmarkOverlay.js)
-    content/browser/places/downloadsViewOverlay.xul      (content/downloadsViewOverlay.xul)
+*   content/browser/places/downloadsViewOverlay.xul      (content/downloadsViewOverlay.xul)