Cherry-pick 259548.773@safari-7615-branch (3d72c32). https://bugs.web…

…kit.org/show_bug.cgi?id=257161

    Follow-up to 259548.752@safari-7615-branch to cancel navigations instead of blocking them
    https://bugs.webkit.org/show_bug.cgi?id=257161
    rdar://108794051

    Reviewed by Alex Christensen.

    259548.752@safari-7615-branch added further restrictions to prevent top-frame navigations
    by third-party iframes, in particular using redirects. I had decided to block the redirect
    with a blockedError(). However, it turns out that Safari shows an error page when doing
    so, which results in a bad user experience since the top frame is still being navigated
    (to an error page).

    To address the issue, I am now cancelling the redirect instead and returning a
    cancelledError(). I have verified that Safari doesn't show an error page in this case and
    that the top frame is not getting navigated.

    * Source/WebCore/loader/DocumentLoader.cpp:
    (WebCore::DocumentLoader::willSendRequest):

    Canonical link: https://commits.webkit.org/259548.773@safari-7615-branch

Source/WebCore/loader/DocumentLoader.cpp

@@ -668,7 +668,7 @@ void DocumentLoader::willSendRequest(ResourceRequest&& newRequest, const Resourc
                         , "'. The frame attempting navigation of the top-level window is cross-origin or untrusted and the user has never interacted with the frame.");
                     m_frame->document()->addConsoleMessage(MessageSource::Security, MessageLevel::Error, message);
                 }
-                cancelMainResourceLoad(frameLoader()->blockedError(newRequest));
+                cancelMainResourceLoad(frameLoader()->cancelledError(newRequest));
                 return completionHandler(WTFMove(newRequest));
             }
         }