Probe the exact Long Animation Frame baseline fields and the Chrome 147 origin-trial split fields. The lab runs real style and layout workloads, then reports either the captured LoAF entry or the explicit performance.measure() fallback.
The split fields are expected to be absent unless LongAnimationFrameStyleDuration is enabled. A correct fallback keeps styleAndLayoutStart and scripts[].forcedStyleAndLayoutDuration visible instead of showing blank results.