Probably, The version that Tesla seems to be using isn't actually 5.1 (or maybe it was pre-5.1) so it is probably that WebGL wasn't included. I am still looking for an alternative to display CPU/GPU info.
IIRC back in 2011, WebKit was still only being delivered by Apple in those tarballs-every-major-OS-release drops on open source.apple.com, and those were heavily redacted too especially for ARM.
I'm actually surprised that QtWebKit ran as well as it did for ARM, but I don't even think the real iOS JIT was in that old build of WebKit, so it might've just been interpreted Javascript at the time.