examples(webgl): stop using old window static methods

These were removed and replaced with normal methods on window and a standalone
function to get the global window.

Author: fitzgen

examples/webgl/src/lib.rs

@@ -8,7 +8,7 @@ use web_sys::{WebGlProgram, WebGlRenderingContext, WebGlShader};
 
 #[wasm_bindgen]
 pub fn draw() {
-    let document = web_sys::Window::document().unwrap();
+    let document = web_sys::window().unwrap().document().unwrap();
     let canvas = document.get_element_by_id("canvas").unwrap();
     let canvas: web_sys::HtmlCanvasElement = canvas
         .dyn_into::<web_sys::HtmlCanvasElement>()