Wrapping bot.frame.defaultContent in anonymous function

In the injected case, we are not interested in the returned wrapped window
object. In point of fact, other atoms can get confused by this. Wrapping
in an anonymous function prevents this.

javascript/webdriver/atoms/inject/frame.js

@@ -68,7 +68,11 @@ webdriver.atoms.inject.frame.findFrameByIndex = function(index, opt_root) {
  *     which is the top window.
  */
 webdriver.atoms.inject.frame.defaultContent = function() {
-  return webdriver.atoms.inject.executeScript(bot.frame.defaultContent, []);
+  // When calling bot.frame.defaultContent in the injected case,
+  // we don't care about the wrapped window object, so we can
+  // wrap the atom here.
+  return webdriver.atoms.inject.executeScript(
+    function() { bot.frame.defaultContent(); }, []);
 };