У вашего броузера проблема в совместимости с HTML5
See how you can activate the hidden feature of skeletal animation for your 2D Characters and experiment with Inverse Kinematics in Unity.
I will teach you the basic knowledge for Unitys prefered future method of 2D Animation.
All you need is to download the 2018 beta version:
https://unity3d.com/unity/beta
and the example project from this link, where you will also find a detailed documentation and advice how to activate the feature for your own project.
https://github.com/Unity-Technologies/2d-animation-samples
You can also follow the progress of this Phase 1 experimental preview in the Unity forum:
https://forum.unity.com/threads/2d-animation-preview-packages.521778/