merge_pr_50325

Check the requestMethod field with addRoutes()

As proposed in w3c/ServiceWorker#1747,
let me make the Chromium validate the requestMethod with
https://fetch.spec.whatwg.org/#concept-method and
https://fetch.spec.whatwg.org/#forbidden-method

There is also ongoing spec change in:
w3c/ServiceWorker#1748

Change-Id: I34b4ebb467b7e45bf36d972764c2cfaf8b059019
Bug: 391722219
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6191305
Reviewed-by: Keita Suzuki [email protected]
Reviewed-by: Shunya Shishido [email protected]
Reviewed-by: Takashi Toyoshima [email protected]
Commit-Queue: Yoshisato Yanagisawa [email protected]
Reviewed-by: Minoru Chikamune [email protected]
Cr-Commit-Position: refs/heads/main@{#1412047}