amlPane.destroy must be called for last pane too

plugins/c9.ide.editors/pane.js

@@ -586,11 +586,11 @@ define(function(require, module, exports) {
                 }
                 
                 if (next) {
-                    // move all pages to another pane
+                    // move all pages to another pane if there is one
                     getTabs().forEach(function(tab) {
                         tab.attachTo(next.cloud9pane, null, true);
                     });
-        
+                }
                 // destroy aml element
                 amlPane.destroy(true, true);
                 
@@ -613,7 +613,6 @@ define(function(require, module, exports) {
                 else {
                     queue = [parent];
                 }
-                }
                 
                 if (last && last.parentNode.localName == "bar") {
                     last.$ext.style.width = "100%";//setAttribute("width", "100%");