[w3c/browser-payment-api] valid decimal monetary value maybe overly restrictive (#304)

Following the [robustness principle](https://en.m.wikipedia.org/wiki/Robustness_principle), if monetary values are strings, the algorithm for "valid decimal monetary value" should maybe trim. 

-- 
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/w3c/browser-payment-api/issues/304