all: remove redundant op.TransformOp.Offset

Use op.Offset instead, or create and manipulate a f32.Affine2D.

API change. Update your code with a gofmt rule:

	gofmt -r 'op.TransformOp{}.Offset -> op.Offset'

Signed-off-by: Elias Naur <mail@eliasnaur.com>

layout/stack.go

@@ -108,7 +108,7 @@ func (s Stack) Layout(gtx Context, children ...StackChild) Dimensions {
 			p.Y = maxSZ.Y - sz.Y
 		}
 		stack := op.Push(gtx.Ops)
-		op.TransformOp{}.Offset(FPt(p)).Add(gtx.Ops)
+		op.Offset(FPt(p)).Add(gtx.Ops)
 		ch.call.Add(gtx.Ops)
 		stack.Pop()
 		if baseline == 0 {