How to change idl specs

This unfortunately can only be done on Windows.

1. If this is a new idl spec, appropriate an iid from xpcom/src/IIDs.h
2. Edit the idl file (e.g. dom/public/idl/range/Range.idl) to make your changes
3. Build idlc.exe: cd dom/tools; nmake -f makefile.win
4. In the directory where the idl file lives: nmake -f makefile.win
5. After you've verified that everything still builds, you have three files to check in:
1. dom\public\idl\...\foo\Foo.idl
2. dom\public\xxx\nsIDOMFoo.h
3. dom\src\xxx\nsJSFoo.cpp
(plus any inherited classes you've changed, of course).