(meta) export concepts used in funky element handling

[mozfreddyb]

This is a meta bug for a couple of issues, that we need to fix elsewhere before we can resolve on our end.

• template content is not exported in HTML
• the HTMLHyperLinkElementUtils protocol property is also not properly exported. Also, the protocol getter steps are hairy and need to be moved into its own algorithm, and then we can refer that.
• For the form action case we need to invoke the URL parser ourselves. I think matching on something like javascript: text might not work due to encoding stuff (not entirely sure here).
• The form action is the URL of the document, when empty. Are we OK with this? Do we want to think about the case of javascript documents here? I'd prefer not to, but mentioning for posterity :)

[mozfreddyb]

Most of the above should be resolved by previous work. What's left is:

The form action is the URL of the document, when empty. Are we OK with this? Do we want to think about the case of javascript documents here? I'd prefer not to, but mentioning for posterity :)

In the meeting, we agreed that we can't help that much once the user is in a javascript: document, given that all relative URLs in e.g., href are similarly dangerous. We should add a note to that effect.