Don't add '(' to FUNCTION token names

This patch makes our bison tokenizer parse FUNCTION tokens without the
opening parenthesis. This makes FUNCTIONs with escapes work correctly,
tested in color3.html.

This will be followed up with using CSSValueID for all the strings in
the CSSPropertyParser for Function types. This will provide consistency
with regular keywords, and allow us to remove the code generation in
parsing transforms. In css3-syntax, a function token's value doesn't
include the bracket.

We also change the stored value of pseudo-selectors with arguments to
not include the bracket. This makes no difference since in these cases
we never read the value aside from to parse or serialize it.

BUG=411165

Review URL: https://codereview.chromium.org/603443002

git-svn-id: svn://svn.chromium.org/blink/trunk@182677 bbb929c8-8fbe-4397-9dbb-9b2b20218538