When Firefox loads LayoutTests/fast/parser/xhtml-alternate-entities.xml, it reports a parsing error as follow: "XML Parsing Error: undefined entity Location: file:///Users/joone/git/WebKit/LayoutTests/fast/parser/xhtml-alternate-entities.xml Line Number 4, Column 7: <h1> ƒäïÏ </h1> <!-- If you get a parse error, this test has PASSED. --> ------^ " In case of WebKit based browsers, you can see the following error, "This page contains the following errors: error on line 4 at column 13: Entity 'fnof' not defined Below is a rendering of the page up to the first error." Actually, there is entity 'auml' at column13, so it seems to be wrong information. On the other hand, Firefox seems to report exact information. Anyway, I think LibXML2 may have a problem to report parsing errors.
Is there a spec how to report XML errors? FF reports the first character of the entity, libxml2 the last. So I don't think there's a problem. If you think this is a bug you should report it at the libxml2 bugtracker, because WebKit only shows the error message of the parser library. BTW: IE throws a system error and Opera interprets the it as normal characters.