Move web-sys tests to the new test framework

Migrate most `web-sys` tests to the new `wasm_bindgen_test` framework with the
new headless browser capabilities!

crates/web-sys/tests/wasm/head_element.rs

@@ -0,0 +1,14 @@
+use wasm_bindgen_test::*;
+use wasm_bindgen::prelude::*;
+use web_sys::HtmlHeadElement;
+
+#[wasm_bindgen(module = "./tests/wasm/element.js")]
+extern {
+    fn new_head() -> HtmlHeadElement;
+}
+
+#[wasm_bindgen_test]
+fn test_head_element() {
+    let _element = new_head();
+    assert!(true, "Head doesn't have an interface");
+}