 anti-aliasing and saveLayer immediately following the clip.</p>
<p>This mode not only clips with anti-aliasing, but also allocates an offscreen
buffer. All subsequent paints are carried out on that buffer before finally
being clipped and composited back.</p>
<p>This is very slow. It has no bleeding edge artifacts (that <a href="dart-ui/Clip-class.html">antiAlias</a> has)
but it changes the semantics as an offscreen buffer is now introduced.
(See <a href="https://github.com/flutter/flutter/issues/18057#issu