Add WebIDL support for the object type

This maps to the `Object` type in the `js_sys` crate.

crates/webidl/src/lib.rs

@@ -102,7 +102,7 @@ fn compile_ast(mut ast: backend::ast::Program) -> String {
         vec![
             "str", "char", "bool", "JsValue", "u8", "i8", "u16", "i16", "u32", "i32", "u64", "i64",
             "usize", "isize", "f32", "f64", "Result", "String", "Vec", "Option",
-            "ArrayBuffer",
+            "ArrayBuffer", "Object",
         ].into_iter()
             .map(|id| proc_macro2::Ident::new(id, proc_macro2::Span::call_site())),
     );