Adding a new WebIDL binding

• Add the new webidl file to src/components/script/dom/webidls
• Add an entry to Bindings.conf
• Create your implementation lowercasename.rs in src/components/script/dom - you'll need a #[deriving(Encodable)] struct containing a Reflector at minimum, as well as implementation of the Reflectable trait. Look at blob.rs for a nice, minimal reference.
• Add your implementation to script.rs to ensure it is compiled.
• Build, and fix up any compile errors (such as missing methods or incorrect argument types in your new implementation).

There's an example of a simple HTML element addition which deviates a bit from the above steps.