This benchmark tests how many frames per second the browser is able to draw for a given number of flags. You can increase the number of flags to see the effect on the frame rate. A modern desktop computer should be able to draw at least 20.000 flags (with WebGL) at a smooth frame rate of 60 fps. This benchmark depends on four important factors: The performance of your GPU for the draw calls, the performance of your CPU for the animation, the JavaScript code compiled by dart2js and last but not least the browser you are using.
Compare the benchmark numbers with the HTML5 Version.