[csharp] Port of commit ccc5b2f: Fixed root bone transform for skeleton scale to use world axes. See #1373.

spine-csharp/src/Bone.cs

@@ -149,8 +149,8 @@ namespace Spine {
 			if (parent == null) { // Root bone.
 				float rotationY = rotation + 90 + shearY, sx = skeleton.scaleX, sy = skeleton.scaleY;
 				a = MathUtils.CosDeg(rotation + shearX) * scaleX * sx;
-				b = MathUtils.CosDeg(rotationY) * scaleY * sy;
-				c = MathUtils.SinDeg(rotation + shearX) * scaleX * sx;
+				b = MathUtils.CosDeg(rotationY) * scaleY * sx;
+				c = MathUtils.SinDeg(rotation + shearX) * scaleX * sy;
 				d = MathUtils.SinDeg(rotationY) * scaleY * sy;
 				worldX = x * sx + skeleton.x;
 				worldY = y * sy + skeleton.y;