References to gradients in <style> are not considered as such; the gradients are removed

[Louis Simard]

The file fulltests/scantailor.svg, originally from Ubuntu 10.04's /usr/share/app-install/icons/scantailor.svg and added to trunk revision 181, renders incorrectly after being Scoured.

-- To reproduce --

Program version: trunk revision 180

Command line: ./scour.py --shorten-ids --enable-id-stripping --create-groups --renderer-workaround --indent=none -i fulltests/scantailor.svg -o fulltests/scantailor.opt.svg

[Louis Simard (louis-simard-deactivatedaccount)]

Even with the default command-line options, the fill:url(#idNUMBER) references in <style> aren't being considered as references and the gradients are getting removed from <defs>.

[Louis Simard (louis-simard-deactivatedaccount)]

Debug information added by this patch (not a solution for the bug!) makes the problem more obvious:

A CDATA node may be surrounded by Text nodes if CDATA is surrounded by whitespace, but findReferencedElements considers only the first child node of a <style> element. findReferencedElements therefore ignores the entire stylesheet in this test case.

[Louis Simard (louis-simard-deactivatedaccount)]

This patch has two facets:

1. Allow findReferencedElements to act on a CDATA stylesheet surrounded by whitespace Text nodes.
2. Allow renameID (for shortenIDs) to replace a stylesheet properly.

[Louis Simard (louis-simard-deactivatedaccount)]

Unit tests have been written. The file now renders correctly, and the unit tests both pass.

This fix is in the trunk, revision 184.