This CL renames "extension" to "feature" to follow WebGPU. It still
supports both. A future Chromium CL will pick this change, then all
"extension" occurrences will be removed.
Change-Id: I070e32d7ae042f9b846df01f200b39f6741a0a14
Bug: dawn:1149
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/65664
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>
Commit-Queue: François Beaufort <beaufort.francois@gmail.com>
François Beaufort