message: fix(elements): avoid exception when window is undefined
  Detect server environment by checking `typeof window` and schedule render immediately instead of waiting for RAF.
  This does not make Angular Elements work on platform-server. This is just the first step.
  PR Close
diff: @@ -21,7 +21,7 @@ export const scheduler = {
  * Returns a function that when executed will cancel the scheduled function.
  */
  schedule(taskFn: () => void, delay: number): () =>
  - void{const id = window.setTimeout(taskFn, delay); return () => window.clearTimeout(id);},
  + void{const id = setTimeout(taskFn, delay); return () => clearTimeout(id);},
  /**
  * Schedule a callback to be called before the next render.
  @@ -32,6 +32,11 @@ export const scheduler = {
  scheduleBeforeRender(taskFn: () => void): () => void{
  // TODO(gkalpak): Implement a better way of accessing `requestAnimationFrame()`
  // (e.g. accounting for vendor prefix, SSR-compatibility, etc).
  + if (typeof window === 'undefined') {
  + // For SSR just schedule immediately.
  + return scheduler.schedule(taskFn, 0);
  + }
  +
  if (typeof window.requestAnimationFrame === 'undefined') {
  const frameMs = 16;
  return scheduler.schedule(taskFn, frameMs);
  