Merge pull request #953 from cwillisf/webgl-1-then-2

try WebGL 2.0 if WebGL 1.0 fails

Author: cwillisf

src/RenderWebGL.js

@@ -111,7 +111,12 @@ class RenderWebGL extends EventEmitter {
      * @private
      */
     static _getContext (canvas) {
-        return twgl.getWebGLContext(canvas, {alpha: false, stencil: true, antialias: false});
+        const contextAttribs = {alpha: false, stencil: true, antialias: false};
+        // getWebGLContext = try WebGL 1.0 only
+        // getContext = try WebGL 2.0 and if that doesn't work, try WebGL 1.0
+        // getWebGLContext || getContext = try WebGL 1.0 and if that doesn't work, try WebGL 2.0
+        return twgl.getWebGLContext(canvas, contextAttribs) ||
+            twgl.getContext(canvas, contextAttribs);
     }
 
     /**