> > font-lock-tag-name-face
> > font-lock-tag-bracket-face
>
> These seem very HTML specific, so not really appropriate for font-lock-*-face.
>

I am thinking of markdown, apache-mode, wiki/ini-mode, org-mode (not
sure for this one), and of course all the xml/html modes

>
> > font-lock-attr-name-face
>
> This one probably corresponds to "argument names", so in Lisp it could
> be used for keyword symbols.  IOW I'm OK with adding such a face.
>
> > font-lock-attr-value-face
>
> AFAIK an attribute value is an expression, so I'm not sure why we'd want
> to give it a special face.  I guess it's another way to say that this is
> also too HTML-specific to make much sense for font-lock-*-face.
>
> > font-lock-symbol-face
>
> I have no idea what this one is, neither for HTML nor for any other mode.

I was thinking of this kind of syntax (with js or ruby)

{symbolX: "aa", symbolY: 123}