Tests that top-frame navigations are correctly blocked when intercepted.
intercepted: http://127.0.0.1:8000/inspector-protocol/resources/meta-tag.html, continuing
intercepted: http://127.0.0.1:8000/inspector-protocol/resources/test-page.html, cancelling
location.href = http://127.0.0.1:8000/inspector-protocol/resources/meta-tag.html