Fix remaining warnings

Author: spydon

packages/forge2d/example/web/racer.dart

@@ -1,7 +1,8 @@
-import 'dart:html' hide Body;
+import 'dart:js_interop';
 import 'dart:math';
 
 import 'package:forge2d/forge2d_browser.dart';
+import 'package:web/web.dart';
 
 import 'demo.dart';
 import 'racer/car.dart';
@@ -26,8 +27,8 @@ class Racer extends Demo implements ContactListener {
     _controlState = 0;
 
     // Bind to keyboard events.
-    document.onKeyDown.listen(_handleKeyDown);
-    document.onKeyUp.listen(_handleKeyUp);
+    document.onkeydown = _handleKeyDown.toJS;
+    document.onkeyup = _handleKeyUp.toJS;
 
     // Add ourselves as a collision listener.
     world.setContactListener(this);
@@ -171,8 +172,8 @@ void main() {
   final racer = Racer();
   racer.initialize();
   racer.initializeAnimation();
-  final paragraph = ParagraphElement()
+  final paragraph = HTMLParagraphElement()
     ..innerText = 'Use the arrow keys to drive the car';
-  document.body?.nodes.add(paragraph);
+  document.body?.append(paragraph);
   racer.runAnimation();
 }

packages/forge2d/lib/src/common/canvas_viewport_transform.dart

@@ -1,6 +1,7 @@
-import 'dart:html';
+import 'dart:js_interop';
 
 import 'package:forge2d/forge2d.dart';
+import 'package:web/web.dart';
 
 /// Transform for drawing using a canvas context. Y-flip is permanently set
 /// to true.
@@ -9,7 +10,7 @@ class CanvasViewportTransform extends ViewportTransform {
 
   /// Constructs a new viewport transform with the default scale.
   CanvasViewportTransform(Vector2 extents, Vector2 center)
-      : super(extents, center, defaultDrawingScale) {
+    : super(extents, center, defaultDrawingScale) {
     yFlip = true;
   }
 
@@ -18,7 +19,7 @@ class CanvasViewportTransform extends ViewportTransform {
   /// screen.
   void updateTransformation(CanvasRenderingContext2D ctx) {
     // Clear all previous transformation.
-    ctx.setTransform(1, 0, 0, 1, 0, 0);
+    ctx.setTransform(1.toJS, 0, 0, 1, 0, 0);
 
     // Translate to the center of the canvas screen. This will be considered the
     // actual origin.