Implement CSPEE Blanket Enforcement logic out-of-blink

This changes adds to the AncestorThrottle a check for the step
"Does response allow blanket enforcement of policy from request" of
Content Security Policy: Embedded Enforcement:
https://w3c.github.io/webappsec-cspee/#origin-allowed Behind the flag

This is one of the steps of moving CSPEE out-of-blink and is hidden
under the flag network::features::kOutOfBlinkCSPEE.

Change-Id: Id3092322134e055810d4006e63e6974ee64315be
Bug: 1094909

content-security-policy/embedded-enforcement/support/testharness-helper.sub.js

@@ -17,7 +17,7 @@ const IframeLoad = {
 
 function getOrigin() {
   var url = new URL("http://{{host}}:{{ports[http][0]}}/");
-  return url.toString();
+  return url.origin;
 }
 
 function getCrossOrigin() {