Many operations do not pass refs to Write. Similarly adding

...interface{} requires constructing a slice, which is slow.

This cuts about 100ns from RRect and Border benchmark.

Signed-off-by: Egon Elbre <egonelbre@gmail.com>

op/paint/paint.go

@@ -99,7 +99,7 @@ func (i ImageOp) Add(o *op.Ops) {
 		}.Add(o)
 		return
 	}
-	data := o.Write(opconst.TypeImageLen, i.src, i.handle)
+	data := o.Write2(opconst.TypeImageLen, i.src, i.handle)
 	data[0] = byte(opconst.TypeImage)
 }