Fix vscode debugging

This broke when the TS addon was added

src/addons/search/search.ts

@@ -11,7 +11,7 @@ declare var require: any;
 declare var window: any;
 
 (function (addon) {
-  if ('Terminal' in window) {
+  if (typeof window !== 'undefined' && 'Terminal' in window) {
     /**
      * Plain browser environment
      */
@@ -21,7 +21,7 @@ declare var window: any;
      * CommonJS environment
      */
     module.exports = addon(require('../../xterm'));
-  } else if (typeof define == 'function') {
+  } else if (typeof define === 'function') {
     /**
      * Require.js is available
      */