Fix TS build

Fixes: 8f8813a ("Add PriorityTaskQueue")

src/common/TaskQueue.ts

@@ -22,18 +22,22 @@ interface ITaskQueue {
   clear(): void;
 }
 
+// TimeoutId is a type alias for the return type of setTimeout. NodeJS returns
+// NodeJS.Timeout, the browser returns number.
+type TimeoutId = number | NodeJS.Timeout;
+
 interface ITaskDeadline {
   timeRemaining(): number;
 }
 type CallbackWithDeadline = (deadline: ITaskDeadline) => void;
 
 abstract class TaskQueue implements ITaskQueue {
   private _tasks: (() => void)[] = [];
-  private _idleCallback?: number;
+  private _idleCallback?: TimeoutId;
   private _i = 0;
 
-  protected abstract _requestCallback(callback: CallbackWithDeadline): number;
-  protected abstract _cancelCallback(identifier: number): void;
+  protected abstract _requestCallback(callback: CallbackWithDeadline): TimeoutId;
+  protected abstract _cancelCallback(identifier: TimeoutId): void;
 
   public enqueue(task: () => void): void {
     this._tasks.push(task);
@@ -88,7 +92,7 @@ abstract class TaskQueue implements ITaskQueue {
  * and care should be taken to ensure they're non-urgent and will not introduce race conditions.
  */
 export class PriorityTaskQueue extends TaskQueue {
-  protected _requestCallback(callback: CallbackWithDeadline): number {
+  protected _requestCallback(callback: CallbackWithDeadline): TimeoutId {
     return setTimeout(() => callback(this._createDeadline(16)));
   }