Revert of Add CSP header for resources with an active policy

LayoutTests/http/tests/security/contentSecurityPolicy/resources/csp-header-is-sent.js

-async_test(function(t) {
-    var xhr = new XMLHttpRequest();
-    xhr.onload = function () {
-        t.step(function () { assert_true(xhr.status === 404); t.done(); });
-    };
-    // Send a request that returns 200 if and only if CSP header is present.
-    xhr.open(
-        "GET",
-        "http://127.0.0.1:8000/security/contentSecurityPolicy/resources/test-csp-header.pl",
-        true
-    );
-    xhr.send();
-}, 'CSP header is not sent on resource requests for which there is no policy.');
-
-test(function() {
-    assert_true(typeof(script_loaded) !== "undefined");
-}, 'CSP header is sent on resource requests for which there is a policy.');