Copied tests in ruby version and ported them to javascript syntax.

The original ruby version of htmldiff received some attention in the
past year. I took the tests from myobie/htmldiff@003c74c
from the html_diff_spec.rb, and ported them to javascript regarding
syntax in this commit. Many tests actually fail, because of all sorts of
different behavior. Will check and fix them in a later commit.

Author: Sedeniono