This hook existed because some elements wanted to run script inside
::insertedInto, but that wasn't a safe time. Now nothing can run script
inside there so we don't need this extra hook.
HTMLStyleElement's usage of this hook is not clear, but it seems like
it might have related to a pre-lazy attach bug.
R=abarth@chromium.org
Review URL: https://codereview.chromium.org/758623002
This caused us to lose our gn check certification. :(
Turns out gn check was just ignoring all the header
paths it didn't understand and so gn check passing
for sky wasn't meaning much. I tried to straighten
out some of the mess in this CL, but its going to take
several more rounds of massaging before gn check
passes again. On the bright side (almost) all of
our headers are absolute now. Turns out my script
(attached to the bug) didn't notice ../ includes
but I'll fix that in the next patch.
R=abarth@chromium.org
BUG=435361
Review URL: https://codereview.chromium.org/746023002
