diff --git a/javascript/private/fragment.bzl b/javascript/private/fragment.bzl
index 05cc0f24dc1f2..d5d6ed1b1d7cb 100644
--- a/javascript/private/fragment.bzl
+++ b/javascript/private/fragment.bzl
@@ -51,11 +51,18 @@ def closure_fragment(
 
     # Wrap the output in two functions. The outer function ensures the
     # compiled fragment never pollutes the global scope by using its
-    # own scope on each invocation.
+    # own scope on each invocation. We must import window.navigator into
+    # this unique scope since Closure's goog.userAgent package assumes
+    # navigator and document are defined on goog.global. Normally, this
+    # would be window, but we are explicitly defining the fragment so that
+    # goog.global is _not_ window.
+    #     See http://code.google.com/p/selenium/issues/detail?id=1333
     wrapper = (
         "function(){" +
-        "return (function(){%output%; return this._.apply(null,arguments);}).apply(" +
-        "window, arguments);}"
+        "return (function(){%output%; return this._.apply(null,arguments);}).apply({" +
+        "navigator:typeof window!='undefined'?window.navigator:null," +
+        "document:typeof window!='undefined'?window.document:null" +
+        "}, arguments);}"
     )
 
     browser_defs = {