Are you serious? When's the last time you used ActionScript, 2004? Modern AS3 compiled using the FlexSDK is a proper development environment with compile-time errors for types and all. Combined with a debug player, you get both compile-time and runtime errors.
It certainly has a hell of a lot more error checking going on than something like JavaScript by the virtue of being a statically typed language first with dynamic stuff second.
That's not to say that obscure bugs don't exist in the runtime as with every other runtime ever, but don't misrepresent something you don't seem to be well versed in.
A single bouncing circle on a rectangle doesn't count as a benchmark in my opinion. Flash can be written in a performant manner, it used to be faster than HTML for almost everything, but that gap has narrowed for some specific things.
Most of all though, in my experience, Flash is usually more consistent across browsers and operating systems. Even if it's slower than the fastest browser, it's at least consistently slower.
When dealing with the desktop and/or applications on mobile devices that support AIR (i.e. supported runtimes), graphics rendering isn't an issue anymore. If you are really stuck with poor graphics performance using the traditional methods, you can just leverage Stage3D, which is just like WebGL, except it has a compatibility layer and is constrained in some ways, which can potentially make it more compatible with different underlying architectures and across more GPUs.
Going back to benchmarks though, I believe that 95% (pulled out of my behindus) of benchmarks have poorly written code / code that could be optimized to run an order of magnitude faster, so I won't engage in a benchmark fling-fest. I can at least link a few minor tests I made a while ago where I encountered the above mentioned inconsistency issues:
It certainly has a hell of a lot more error checking going on than something like JavaScript by the virtue of being a statically typed language first with dynamic stuff second.
That's not to say that obscure bugs don't exist in the runtime as with every other runtime ever, but don't misrepresent something you don't seem to be well versed in.