XRWebGLLayer IDL members don't match the specification

[jdm]

Spec: https://immersive-web.github.io/webxr/#xrwebgllayer

[SecureContext, Exposed=Window]
interface XRWebGLLayer: XRLayer {
  constructor(XRSession session,
             XRWebGLRenderingContext context,
             optional XRWebGLLayerInit layerInit = {});
  // Attributes
  readonly attribute boolean antialias;
  readonly attribute boolean ignoreDepthValues;

  [SameObject] readonly attribute WebGLFramebuffer? framebuffer;
  readonly attribute unsigned long framebufferWidth;
  readonly attribute unsigned long framebufferHeight;

  // Methods
  XRViewport? getViewport(XRView view);

  // Static Methods
  static double getNativeFramebufferScaleFactor(XRSession session);
};

XRWebGLLayer.webidl:

[SecureContext, Exposed=Window, Pref="dom.webxr.enabled"]
interface XRWebGLLayer {
  [Throws] constructor(XRSession session,
              XRWebGLRenderingContext context,
              optional XRWebGLLayerInit layerInit = {});
  // // Attributes
  readonly attribute XRWebGLRenderingContext context;

  readonly attribute boolean antialias;
  readonly attribute boolean depth;
  readonly attribute boolean stencil;
  readonly attribute boolean alpha;

  readonly attribute WebGLFramebuffer? framebuffer;
  readonly attribute unsigned long framebufferWidth;
  readonly attribute unsigned long framebufferHeight;

  // // Methods
  XRViewport? getViewport(XRView view);
  // void requestViewportScaling(double viewportScaleFactor);

  // // Static Methods
  // static double getNativeFramebufferScaleFactor(XRSession session);
};

This is breaking WPT webxr tests, because they try to set the context property on the layer and it's readonly.