Extend the ToRenderFrameHost magic to FrameTreeNode* and Shell*.

BUG=None
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_site_isolation

Review-Url: https://codereview.chromium.org/2052633002
Cr-Commit-Position: refs/heads/master@{#398964}
diff --git a/content/browser/security_exploit_browsertest.cc b/content/browser/security_exploit_browsertest.cc
index e225045..a7ba3d7 100644
--- a/content/browser/security_exploit_browsertest.cc
+++ b/content/browser/security_exploit_browsertest.cc
@@ -72,8 +72,7 @@
 
   // Open another window, so we generate some more routing ids.
   ShellAddedObserver shell2_observer;
-  EXPECT_TRUE(ExecuteScript(
-      shell->web_contents(), "window.open(document.URL + '#2');"));
+  EXPECT_TRUE(ExecuteScript(shell, "window.open(document.URL + '#2');"));
   Shell* shell2 = shell2_observer.GetShell();
 
   // The new window must be in the same process, but have a new routing id.