if (VM.VerifyAssertions) VM_Scheduler.assert(t.next == null);
if (VM.VerifyAssertions) VM_Scheduler._assert(t.next == null);
  public void enqueueHighPriority (VM_Thread t) {    if (VM.BuildForEventLogging && VM.EventLoggingEnabled) VM_EventLogger.logEnqueue(t, id);    if (VM.VerifyAssertions) VM_Scheduler.assert(t.next == null); // not currently on any other queue    t.next = head;    head = t;    if (tail == null)       tail = t;  }