We've had problems in the past with bumping past 0.5.2 due to perf
regressions reported by @huacnlee; 0.5.1 was fine though.

Hence, let's bump taffy to 0.5.1 as a safe bet and then try to push past
0.5.2 (after we identify the root cause of regression
Related to #19189
Release Notes:

- N/A