Fix detach with open()ed document leaving parent loading indefinitely

Change-Id: I26c2a054b9f1e5eb076acd677e1223058825f6d6

Bug: 803416
Test: fast/loader/document-open-iframe-then-detach.html
Change-Id: I26c2a054b9f1e5eb076acd677e1223058825f6d6
Reviewed-on: https://chromium-review.googlesource.com/887298
Reviewed-by: Mike West <mkwst@chromium.org>
Commit-Queue: Nate Chapin <japhet@chromium.org>
Cr-Commit-Position: refs/heads/master@{#532967}
void DocumentLoader::Trace(blink::Visitor* visitor) {
  visitor->Trace(frame_);
  visitor->Trace(fetcher_);
  visitor->Trace(history_item_);
  visitor->Trace(parser_);
  visitor->Trace(subresource_filter_);
  visitor->Trace(document_load_timing_);
  visitor->Trace(application_cache_host_);
  visitor->Trace(content_security_policy_);
  RawResourceClient::Trace(visitor);
}

void DocumentLoader::Trace(blink::Visitor* visitor) {
  visitor->Trace(frame_);
  visitor->Trace(fetcher_);
  visitor->Trace(history_item_);
  visitor->Trace(parser_);
  visitor->Trace(subresource_filter_);
  visitor->Trace(document_load_timing_);
  visitor->Trace(application_cache_host_);
  visitor->Trace(content_security_policy_);
  RawResourceClient::Trace(visitor);
}
