Draft web platform structure

src/platform_impl/web/stdweb/canvas.rs

@@ -0,0 +1,20 @@
+pub struct Canvas;
+
+impl Canvas {
+    pub fn new() -> Self {
+        let element = document()
+            .create_element("canvas")
+            .map_err(|_| os_error!(OsError("Failed to create canvas element".to_owned())))?;
+
+        let canvas: CanvasElement = element
+            .try_into()
+            .map_err(|_| os_error!(OsError("Failed to create canvas element".to_owned())))?;
+
+        document()
+            .body()
+            .ok_or_else(|| os_error!(OsError("Failed to find body node".to_owned())))?
+            .append_child(&canvas);
+
+        Canvas(canvas)
+    }
+}