the y coordinate of the translation, minus the <code>ssin</code>
argument multiplied by the x-coordinate of the rotation point, minus the
<code>scos</code> argument multiplied by the y-coordinate of the rotation point.</p>
<p>The <a href="dart-ui/RSTransform/RSTransform.fromComponents.html">RSTransform.fromComponents</a> method may be a simpler way to
construct these values. However, if there is a way to factor out the
computations of the sine and cosine of the rotation so that they can be
reused over multi