nsIToolkitChromeRegistry in Firefox 3.5

 If the OS has a "high-visibility" or "disabled-friendly" theme set,
 we want to force mozilla into the classic theme, which (for the most part
 obeys the system color/font settings. We cannot do this at initialization,
 because it depends on the toolkit (GTK2) being initialized, which is
 not the case in some embedding situations. Embedders have to manually
 call this method during the startup process.

 Get a list of locales available for the specified package.

 The "canonical" manifest is a plaintext file which sits outside of a
 JAR file. To provide backwards-compatibility with contents.rdf, we provide
 this function which reads a contents.rdf manifest and writes it to a file.

 @param aOldManifestURI  The URI of an old manifest to read, without
                         the trailing "contents.rdf", e.g.
                         "jar:resource:///chrome/foo.jar!/content/foo/" or
                         "file://path/to/contents/rdf/"
 @param aFile            The URI of a manifest file to write. It's a good
                         idea to use a resource: URI if possible.
 @param aBaseURI         The base URI for relative path creation
                         "jar:resource:///chrome/foo.jar!/content/foo/"
                         this is a separate param from aOldManifestURI so
                         the "contents.rdf" can be read outside of the jar
                         to keep the zipreader cache from holding it open.
 @param aAppend          Whether we should append to an existing manifest
                         or truncate and start empty.
 @param aSkinOnly        Only allow skin packages.