Fix quaternion to euler bug

[cptbtptpbcptdtptp]

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The derivation process：

1. Use YXZ Order and expand matrix elements：https://github.com/mrdoob/three.js/blob/ce756225c802ff24cc27a1f615cc9bf420023ae8/src/math/Euler.js#L134
2. Convert normalized version to non-normalized version ：http://www.euclideanspace.com/maths/geometry/rotations/conversions/quaternionToEuler/

[cptbtptpbcptdtptp]

Referenced ThreeJS processing of converting Quaternion to Euler:
https://github.com/mrdoob/three.js/blob/ce756225c802ff24cc27a1f615cc9bf420023ae8/src/math/Euler.js#L200

				this._z = Math.asin( clamp( m21, - 1, 1 ) );

				if ( Math.abs( m21 ) < 0.9999999 ) {

					this._x = Math.atan2( - m23, m22 );
					this._y = Math.atan2( - m31, m11 );

				} else {

					this._x = 0;
					this._y = Math.atan2( m13, m33 );

				}

Combined with non-normalized Quaternion:

http://www.euclideanspace.com/maths/geometry/rotations/conversions/quaternionToEuler/