Allow web-sys to emit correct typescript declarations from webidl (#1998)

* Update to emit typescript names

* Update to use NamedAnyref

* Update incoming / outgoing

* Remove added space

* Remove comment

* Add basic typescript tests for web-sys

crates/typescript-tests/src/lib.rs

@@ -4,3 +4,4 @@ pub mod opt_args_and_ret;
 pub mod optional_fields;
 pub mod simple_fn;
 pub mod simple_struct;
+pub mod web_sys;

crates/typescript-tests/src/web_sys.rs

@@ -0,0 +1,24 @@
+use wasm_bindgen::prelude::*;
+use web_sys::*;
+
+#[wasm_bindgen]
+pub struct DocStruct {
+    doc: Document,
+}
+
+#[wasm_bindgen]
+impl DocStruct {
+    pub fn new(doc: Document) -> Self {
+        Self { doc }
+    }
+
+    pub fn get_doc(&self) -> Document {
+        self.doc.clone()
+    }
+
+    pub fn append_element(&self, element: &HtmlElement) {
+        self.doc.body().unwrap().append_child(element).unwrap();
+    }
+
+    pub fn append_many(&self, _: &HtmlElement, _: &HtmlElement, _: &HtmlElement) {}
+}

crates/typescript-tests/src/web_sys.ts

@@ -0,0 +1,26 @@
+import * as wbg from "../pkg/typescript_tests";
+
+const doc: Document = document;
+
+const docStruct = wbg.DocStruct.new(doc);
+
+const el: HTMLElement = document.createElement("a");
+
+docStruct.append_element(el);
+docStruct.append_many(el, el, el);
+
+const newDoc = docStruct.get_doc();
+
+// This test ensures that the correct Typescript types are
+// used. If "newDoc" is "any", then "event" will cause the
+// compilation to fail because of noImplicitAny.
+newDoc.addEventListener("load", event => {
+  console.log(event);
+});
+
+// Same as above, but testing that the param is a document.
+const listener: Parameters<
+  Parameters<typeof wbg["DocStruct"]["new"]>[0]["addEventListener"]
+>[1] = event => console.log(event);
+
+newDoc.addEventListener("load", listener);