Remove WebFrame::canHaveSecureChild

To simplify the public API, ServiceWorkerNetworkProvider can do the
parent walk itself.

Follow-up to https://crrev.com/ad1850962644e19.

BUG=607543

Review-Url: https://codereview.chromium.org/2082493002
Cr-Commit-Position: refs/heads/master@{#400896}
void Document::activeChainNodeDetached(Element& element)
{
    if (!m_activeHoverElement)
        return;

    if (element != m_activeHoverElement)
        return;

    Node* activeNode = FlatTreeTraversal::parent(element);
    while (activeNode && activeNode->isElementNode() && !activeNode->layoutObject())
        activeNode = FlatTreeTraversal::parent(*activeNode);

    m_activeHoverElement = activeNode && activeNode->isElementNode() ? toElement(activeNode) : 0;
}

void Document::activeChainNodeDetached(Element& element)
{
    if (!m_activeHoverElement)
        return;

    if (element != m_activeHoverElement)
        return;

    Node* activeNode = FlatTreeTraversal::parent(element);
    while (activeNode && activeNode->isElementNode() && !activeNode->layoutObject())
        activeNode = FlatTreeTraversal::parent(*activeNode);

    m_activeHoverElement = activeNode && activeNode->isElementNode() ? toElement(activeNode) : 0;
}
