exp/html: adjust beforeHTMLIM to match spec
exp/html: adjust beforeHTMLIM to match spec

Add case for doctype tokens (which are ignored).

This CL does not change the status of any tests.

R=golang-dev, nigeltao
CC=golang-dev
http://codereview.appspot.com/6061047

Committer: Nigel Tao <58ae08b3356928ff9c67562b4719487d54fe8348@golang.org>

apparentlymart/golang,pombredanne/go-deleteme,gnanderson/go,tv42/old-go,gnanderson/go,pombredanne/go-deleteme,dsriram/golang,apparentlymart/golang,pombredanne/go-deleteme,dsriram/golang,gnanderson/go,dsriram/golang,tv42/old-go,gnanderson/go,dsriram/golang,tv42/old-go,tv42/old-go,pombredanne/go-deleteme,pombredanne/go-deleteme,apparentlymart/golang,gnanderson/go,tv42/old-go,apparentlymart/golang,apparentlymart/golang,dsriram/golang,dsriram/golang,pombredanne/go-deleteme,apparentlymart/golang,dsriram/golang,gnanderson/go,tv42/old-go,apparentlymart/golang,gnanderson/go,pombredanne/go-deleteme,tv42/old-go