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::cloneDataFromDocument(const Document& other)
{
    setCompatibilityMode(other.getCompatibilityMode());
    setEncodingData(other.m_encodingData);
    setContextFeatures(other.contextFeatures());
    setSecurityOrigin(other.getSecurityOrigin()->isolatedCopy());
    setMimeType(other.contentType());
}

void Document::cloneDataFromDocument(const Document& other)
{
    setCompatibilityMode(other.getCompatibilityMode());
    setEncodingData(other.m_encodingData);
    setContextFeatures(other.contextFeatures());
    setSecurityOrigin(other.getSecurityOrigin()->isolatedCopy());
    setMimeType(other.contentType());
}
