Performance/audit of pages like Interop

[bkardell]

I'm not sure about all of the rest of wpt.fyi but at least some pages, like interop page seem straightforward enough and widely shared and linked enough that it's worth looking at an audit and the devtools... It seems to me that it shouldn't take 129 javascript files requested (unminified) individually (and in many cases sequentially discovered) to show that page, for example, but I think that is what I am seeing here currently... Not sure what else we'll find I just happened to have dev tools open while hitting the Interop page and observed this much and was suprised. Lots of these are fairly old problems too - like using polymer and shady dom so there are some linked issues like #2986 which would probably help already