detailed comment added

git-svn-id: svn://svn.code.sf.net/p/htmlunit/code/trunk@9454 5f5364db-9458-4db8-a492-e30667be6df6
URISyntaxException thrown while trying to load valid URL (invalid percent sign escaping)

git-svn-id: svn://svn.code.sf.net/p/htmlunit/code/trunk@9455 5f5364db-9458-4db8-a492-e30667be6df6
JavaScript: Image.complete support added.

git-svn-id: svn://svn.code.sf.net/p/htmlunit/code/trunk@9456 5f5364db-9458-4db8-a492-e30667be6df6