スクリプトでAnimationClipのLoopTimeを変更する

using UnityEngine;
using UnityEditor;

public class NewBehaviourScript
{
    [MenuItem("Assets/Enable Loop Time")]
    static void EnableLoopTime ()
    {
        var clip = Selection.activeObject as AnimationClip;
        var serialied = new SerializedObject (clip);
        serialied.FindProperty ("m_AnimationClipSettings.m_LoopTime").boolValue = true;
        serialied.ApplyModifiedProperties ();
    }
}