[whatwg] <iframe srcdoc> definition not compatible with existing user-agent user interfaces

[Boris Zbarsky]

The way <iframe srcdoc> is defined, the document URI does not in any way 
encode the document contents.

Unfortunately, that breaks user-agent and extension features like "open 
frame in new window", "show only this frame", "open frame in new tab", etc.

I just tried this in the two UAs I have that implement such features, 
and Chrome simply doesn't have such options in its default UI, while in 
Safari those context menu options are in fact just completely broken.

This seems fairly undesirable.  Is there a reason we don't want a URI 
which _will_ encode the source in some way so as to avoid breaking basic 
UI like this?

-Boris