fix(vtkOpenGLRenderWindow): Remove unused HaveVRDisplay event

Removes `vtkOpenGLRenderWindow.HaveVRDisplay` event. This event is
unused internally and was previously left over from WebVR to WebXR
integration to avoid API breakage.

Under previous behavior the `navigator.xr` check was called eagerly
at construction, which could result in an unhandled exception. This
change removes that eager check so that `navigator.xr` is referenced
only if an XR-related method such as `startXR` is called.

Applications should query `navigator.xr` directly to determine whether a
given session type may be supported.

Resolves #2537

Author: tbirdso

Sources/Rendering/OpenGL/RenderWindow/index.js

@@ -107,11 +107,6 @@ function vtkOpenGLRenderWindow(publicAPI, model) {
     false
   );
 
-  // Cache the value here as calling it on each frame is expensive
-  const isImmersiveVrSupported =
-    navigator.xr !== undefined &&
-    navigator.xr.isSessionSupported('immersive-vr');
-
   // Auto update style
   const previousSize = [0, 0];
   function updateWindow() {
@@ -263,11 +258,6 @@ function vtkOpenGLRenderWindow(publicAPI, model) {
   ) => {
     let result = null;
 
-    // Do we have webxr support
-    if (isImmersiveVrSupported) {
-      publicAPI.invokeHaveVRDisplay();
-    }
-
     const webgl2Supported = typeof WebGL2RenderingContext !== 'undefined';
     model.webgl2 = false;
     if (model.defaultToWebgl2 && webgl2Supported) {
@@ -1367,7 +1357,6 @@ export function extend(publicAPI, model, initialValues = {}) {
   model.renderPasses[0] = vtkForwardPass.newInstance();
 
   macro.event(publicAPI, model, 'imageReady');
-  macro.event(publicAPI, model, 'haveVRDisplay');
 
   // Build VTK API
   macro.get(publicAPI, model, [