Bug 1365638 - Use a different string for the sidebar close buttons label and tooltip;r=dao

MozReview-Commit-ID: 1jXU170RXbQ

--HG--
extra : rebase_source : c440d20c5b3094d02a33b8e53d89d20399bbe79e

browser/base/content/browser.xul

@@ -320,7 +320,7 @@
          <observes element="viewTabsSidebar" attribute="checked"/>
        </toolbarbutton>
       <toolbarseparator/>
-      <toolbarbutton label="&sidebarCloseButton.tooltip;"
+      <toolbarbutton label="&sidebarMenuClose.label;"
                      class="subviewbutton"
                      oncommand="SidebarUI.hide()"/>
     </panel>

browser/locales/en-US/chrome/browser/browser.dtd

@@ -667,6 +667,7 @@ you can use these alternative items. Otherwise, their values should be empty.  -
 <!ENTITY fullZoom.accesskey             "Z">
 
 <!ENTITY sidebarCloseButton.tooltip     "Close sidebar">
+<!ENTITY sidebarMenuClose.label         "Close Sidebar">
 
 <!ENTITY quitApplicationCmdWin2.label       "Exit">
 <!ENTITY quitApplicationCmdWin2.accesskey   "x">