Draft web platform structure

src/platform_impl/web/web_sys/mod.rs

@@ -0,0 +1,17 @@
+mod canvas;
+mod document;
+mod timeout;
+
+pub use self::canvas::Canvas;
+pub use self::document::Document;
+pub use self::timeout::Timeout;
+
+pub fn request_animation_frame<F>(f: F)
+where
+    F: Fn(),
+{
+}
+
+pub fn throw(msg: &str) {
+    wasm_bindgen::throw_str(msg);
+}