js2-mode uses -face suffix for faces.
We are not using this suffix anymore and the tree has been cleaned up of
such with backward compatibility code added. This is new code, so
there's little point in having the suffix...
Agree; I'll fix it. The docs (info pages) are incorrect on a relevant point,
incidentally; they claim that defining variables whose value is set to the
face of the same name is popular but obsolete; the reality is that
font-lock-add-keywords requires the variable definitions.
Also, instead of defining a new js2-error-face why not just use
font-lock-warning-face?
and the modes will follow.