(...and ASSERT_NOT_REACHED => VERIFY_NOT_REACHED)
Since all of these checks are done in release builds as well,
let's rename them to VERIFY to prevent confusion, as everyone is
used to assertions being compiled out in release.
We can introduce a new ASSERT macro that is specifically for debug
checks, but I'm doing this wholesale conversion first since we've
accumulated thousands of these already, and it's not immediately
obvious which ones are suitable for ASSERT.
This should really be a WindowProxy? but since we don't have anything
representing that concept yet, let's just expose the Window object
directly so document.defaultView.foo works. :^)
Document and HTMLElement now inherit from HTML::GlobalEventHandlers
which allows them to support "onfoo" event handler attributes.
These are assignable both via IDL attributes and content attributes.
Event listeners constructed this way get a special "attribute" flag
on them so we know which one to replace if you reassign them.
This also allows them to coexist with EventTarget.addEventListener().
This is all a bit sloppy, but it works decently for a first cut.
The Window object should also inherit GlobalEventHandlers, but since
we don't generate it from IDL, I haven't taken that step here.
Also this would be a lot nicer if we supported IDL mixins.
This fills in a bunch of the FIXMEs that was in prepare_script.
execute_script is almost finished, it's just missing the module side.
As an aside, let's not assert when inserting a script element with
innerHTML.
