Disable frame navigations during DocumentLoader detach in FrameLoader::startLoad

BUG=613266

Review-Url: https://codereview.chromium.org/2006033002
Cr-Commit-Position: refs/heads/master@{#396241}
bool HTMLAnchorElement::hasRel(uint32_t relation) const
{
    return m_linkRelations & relation;
}

bool HTMLAnchorElement::hasRel(uint32_t relation) const
{
    return m_linkRelations & relation;
}
