Ah snap! There was no error compiling the test kernel or running it, but the numbers don't check out. Please report your browser (+ version) and hardware configuration to us, so we can try to fix this. Deviation was 0.01766666672968616.

Safari Version 10.0.1 (12602.2.14.0.7)
MacOS Sierra 10.12.1
MacBook Pro late 2012
Intel HD Graphics 4000 1536 MB