html: refactor parse test infrastructure
html: refactor parse test infrastructure

My excuse for doing this is that test cases with newlines in them didn't
work. But instead of just fixing that, I rearranged everything in
parse_test.go to use fewer channels and pipes, and just call a
straightforward function to read test cases from a file.

R=nigeltao
CC=golang-dev
http://codereview.appspot.com/5410049

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

mhennings/marcohennings-go,webfd/go-zh,scirelli/scirelli-go,rdp/rogerpack2005-golang,rflanagan/reginaldflanagan-project1,glycerine/jeaten-go-arrayof-structof,rdp/rogerpack2005-golang,glycerine/jeaten-go-arrayof-structof,scirelli/scirelli-go,sanjosh/sanjos100-tipc,Triskite/willstone-goclone,sanjosh/sanjos100-tipc,d0f/go-zh,bryanxu/go-zh,d0f/go-zh,webfd/go-zh,rdp/rogerpack2005-golang,scirelli/scirelli-go,mhennings/marcohennings-go,scirelli/scirelli-go,Triskite/willstone-goclone,glycerine/jeaten-go-arrayof-structof,webfd/go-zh,rflanagan/reginaldflanagan-project1,Triskite/willstone-goclone,sanjosh/sanjos100-tipc,rflanagan/reginaldflanagan-project1,Triskite/willstone-goclone,glycerine/jeaten-go-arrayof-structof,bryanxu/go-zh,rdp/rogerpack2005-golang,rflanagan/reginaldflanagan-project1,Triskite/willstone-goclone,bryanxu/go-zh,sanjosh/sanjos100-tipc,scirelli/scirelli-go,d0f/go-zh,rflanagan/reginaldflanagan-project1,glycerine/jeaten-go-arrayof-structof,d0f/go-zh,scirelli/scirelli-go,webfd/go-zh,d0f/go-zh,rdp/rogerpack2005-golang,glycerine/jeaten-go-arrayof-structof,mhennings/marcohennings-go,rflanagan/reginaldflanagan-project1,glycerine/jeaten-go-arrayof-structof,d0f/go-zh,glycerine/jeaten-go-arrayof-structof,Triskite/willstone-goclone,sanjosh/sanjos100-tipc,rflanagan/reginaldflanagan-project1,d0f/go-zh,bryanxu/go-zh,webfd/go-zh,Triskite/willstone-goclone,mhennings/marcohennings-go,rdp/rogerpack2005-golang,d0f/go-zh,mhennings/marcohennings-go,mhennings/marcohennings-go,sanjosh/sanjos100-tipc,bryanxu/go-zh,sanjosh/sanjos100-tipc,mhennings/marcohennings-go,webfd/go-zh,Triskite/willstone-goclone,rflanagan/reginaldflanagan-project1,bryanxu/go-zh,webfd/go-zh,rdp/rogerpack2005-golang,webfd/go-zh,bryanxu/go-zh,scirelli/scirelli-go,sanjosh/sanjos100-tipc,rdp/rogerpack2005-golang,bryanxu/go-zh,mhennings/marcohennings-go,scirelli/scirelli-go