Fix links in sidebar (bug 25951).

suite/common/sidebar/sidebarOverlay.xul

@@ -56,7 +56,7 @@
           </rule>
         </template>
       </box>
-      <html:iframe id="sidebar-content" content="true" src="about:blank" 
+      <html:iframe id="sidebar-content" type="content" src="about:blank" 
         class="panel-frame" flex='1*'/>
       <box id="sidebar-panels-bottom" align="vertical"
         datasources="chrome://sidebar/content/local-panels.rdf chrome://sidebar/content/remote-panels.rdf">