cajole_html is refusing <a href="#foo">

cajole_html uses a unique PluginEnvironment
that allows limited filesystem references,
but barfs on most uses of #fragments.

this change relaxes the restriction on #fragments.
so now <a href="#foo"> is allowed,
and if href="foo.html" is allowed,
then href="foo.html#bar" is also allowed.

there's no testcase in this change because there
isn't already a test structure for any of this.
(emma says 0% coverage)
I might add tests later.

[ihab.awad, 2009-07-10 18:58:10]

LGTM

http://codereview.appspot.com/88149/diff/1/2
File src/com/google/caja/plugin/FileSystemEnvironment.java (right):

http://codereview.appspot.com/88149/diff/1/2#newcode70
Line 70: String uristr = self.relativize(ref.getUri()).toString();
Ok, I see now how you worked around the fact that the cajoler is
pre-absolutizing the fragment, and I now see how it should not do that. Ziqing
Mao also just pointed out to me that ExternalReference *already* contains a
pair: the source FilePosition and the target URI. Check. :) So ok, we should
just fix the cajoler attribute rewriting code.