message: PriorityQueue now iterable.
diff: @@ -187,10 +187,8 @@ class Queue extends PriorityQueue<Request> {
  super((lhs, rhs) => lhs.priority - rhs.priority);
  }
  - public get array(): Request[] { return this._array; }
  -
  public has(request: Request): boolean {
  - return this.array.indexOf(request) >= 0;
  + return this._array.indexOf(request) >= 0;
  }
  }
  @@ -330,7 +328,7 @@ class RequestScheduler implements TileRequest.Scheduler {
  return;
  // Cancel any previously pending requests which are no longer needed.
  - for (const queued of previouslyPending.array)
  + for (const queued of previouslyPending)
  if (queued.viewports.isEmpty)
  this.cancel(queued);
  @@ -421,7 +419,7 @@ class RequestScheduler implements TileRequest.Scheduler {
  this._activeRequests.clear();
  - for (const queued of this._pendingRequests.array)
  + for (const queued of this._pendingRequests)
  queued.cancel(this);
  this._requestsPerViewport.clear();
  