Get rid of appCore from sessionHistoryUI.js again, hyatt's recent changes of saving the sessionHistory object on skin switching makes this possible.

bug=46200, r=alecf, a=ben

xpfe/browser/resources/content/sessionHistoryUI.js

@@ -23,7 +23,7 @@
  *  Peter Annema <disttsc@bart.nl>
  *
  */
-const MAX_HISTORY_MENU_ITEMS = 15
+const MAX_HISTORY_MENU_ITEMS = 15;
 const MAX_HISTORY_ITEMS = 100;
 var rdf = Components.classes["@mozilla.org/rdf/rdf-service;1"]
              .getService(Components.interfaces.nsIRDFService);
@@ -37,24 +37,7 @@ function FillHistoryMenu( aParent, aMenu )
     var browserElement = document.getElementById("content");
     if (browserElement)
       {
-	     var foopy = { }; 
-         var ds;
-		 var docShell;
-		 // Try to get docshell from appCore so that go/forward/back
-		 // menus work right after a theme switch. If fetching from
-		 // appCore fails use, the original method,
-         if (appCore) {
-		    appCore.getContentDocShell(foopy); 
-            ds = foopy.value; 
-		 }
-		 if (ds) {
-		    dump("Got docshell from appCOre\n");
-		    docShell = ds;
-		 }
-	     else
-            docShell = browserElement.boxObject.QueryInterface(Components.interfaces.nsIBrowserBoxObject).docShell;
-        if (docShell) {        
-		    var webNavigation = docShell.QueryInterface(Components.interfaces.nsIWebNavigation);
+        var webNavigation = browserElement.webNavigation;
         if (webNavigation)
           {
             var shistory = webNavigation.sessionHistory;
@@ -102,7 +85,6 @@ function FillHistoryMenu( aParent, aMenu )
           }
       }
   }
-  }
 
 function executeUrlBarHistoryCommand( aTarget )
   {
@@ -117,7 +99,6 @@ function executeUrlBarHistoryCommand( aTarget)
 
 function createUBHistoryMenu( aParent )
   {
-    var ubHistory = appCore.urlbarHistory;
     if (localstore) {
       var entries = rdfc.MakeSeq(localstore, rdf.GetResource("nc:urlbar-history")).GetElements();
       var i= MAX_HISTORY_MENU_ITEMS;
@@ -145,7 +126,6 @@ function createUBHistoryMenu( aParent )
 
 function addToUrlbarHistory()
   {
-    //var ubHistory = appCore.urlbarHistory;
 	var urlToAdd = gURLBar.value;
 	if (!urlToAdd)
 	   return;