Make gl-react-dom fallback to "webgl" when "webgl2" fails

By default, we'll do "auto" compatible mode until Safari supports webgl2.
This behavior can be overriden if needed by forcing version="webgl2" or version="webgl" on the Surface. it will implicitly be version="auto" until 100% browser supports webgl2.

Author: gre

packages/gl-react-dom/src/GLViewDOM.js

@@ -176,7 +176,7 @@ export default class GLViewDOM extends Component<
       debug
         ? { ...webglContextAttributes, preserveDrawingBuffer: true }
         : webglContextAttributes,
-      version || "webgl2"
+      version || "auto"
     );
     this.webglContextAttributes = webglContextAttributes || {};
     return gl;

packages/gl-react-dom/src/getContext.js

@@ -1,10 +1,19 @@
-export default (
+const getContext = (
   canvas: HTMLCanvasElement,
   opts: any,
-  version: "webgl" | "webgl2"
-) =>
-  version === "webgl2"
-    ? canvas.getContext("webgl2", opts)
-    : canvas.getContext("webgl", opts) ||
+  version: "webgl" | "webgl2" | "auto"
+) => {
+  let gl;
+  if (version === "webgl2" || version === "auto") {
+    gl = canvas.getContext("webgl2", opts);
+  }
+  if (!gl && (version === "webgl" || version === "auto")) {
+    gl =
+      canvas.getContext("webgl", opts) ||
       canvas.getContext("webgl-experimental", opts) ||
       canvas.getContext("experimental-webgl", opts);
+  }
+  return gl;
+};
+
+export default getContext;