As part of this change I made codegen synchronous. Technically is not necessary,
but I think it reduces complexity a lot. For example, keeping it async would
have required more changes to the testing infrastructure. Let me know if you
want to keep that change separate though.
With this change, I'm removing one more use of element.node, which is necessary
to achileve our goal. There is only one more use of this API, for which John has
a CL out.
BUG=
R=jmesserly@google.com
Review URL: https://chromereviews.googleplex.com/145167013
Sigmund Cherem
763e61f4d3