Refactor TemplateCompiler to make it easier to reuse the attribute sanitizer

To make it easier to reuse the HTML attribute sanitizer, I moved
all the code in TemplateCompiler that dealt with attribute values
into a separate class: HtmlAttributeRewriter.

I created HtmlAttributeRewriter by doing (svn cp ...) so you should
be able to see the diffs between the two files which should be more
instructive than reading HtmlAttributeRewriter line by line.

I also reorganized the code that generates expressions from strings
and dynamic bits, since that's critical to generating code from
templates.  See JsConcatenator.

Also simplified CssRewriter -- it requires a PluginEnvironment but
nothing else from PluginMeta.


Submitted @3667

[metaweta, 2009-08-27 20:48:53]

LGTM

http://codereview.appspot.com/109100/diff/1/4
File tests/com/google/caja/plugin/templates/JsConcatenatorTest.java (right):

http://codereview.appspot.com/109100/diff/1/4#newcode85
Line 85: "new Date(year, month, day)");
Maybe also test "+ new Date", which returns a number.

[MikeSamuel, 2009-08-27 20:54:27]

http://codereview.appspot.com/109100/diff/1/4
File tests/com/google/caja/plugin/templates/JsConcatenatorTest.java (right):

http://codereview.appspot.com/109100/diff/1/4#newcode85
Line 85: "new Date(year, month, day)");
On 2009/08/27 20:48:53, metaweta wrote:
> Maybe also test "+ new Date", which returns a number.

Done.