Add support for the "webidentity" fetch destination

See whatwg/fetch#1495

Bug: 1368382
Change-Id: I298988f78fb10e21ccc83dde9f218f1371c676d1
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3931069
Commit-Queue: Christian Biesinger <cbiesinger@chromium.org>
Reviewed-by: Finnur Thorarinsson <finnur@chromium.org>
Reviewed-by: Reilly Grant <reillyg@chromium.org>
Reviewed-by: Sophie Chang <sophiechang@chromium.org>
Reviewed-by: Daniel Rubery <drubery@chromium.org>
Reviewed-by: Mike West <mkwst@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1054725}
NOKEYCHECK=True
GitOrigin-RevId: 2f45baa7de4e77ab72424192e7b4f9f659455ae6

blink/renderer/platform/loader/fetch/url_loader/web_url_loader.cc

@@ -986,6 +986,7 @@ net::NetworkTrafficAnnotationTag WebURLLoader::Context::GetTrafficAnnotationTag(
     case network::mojom::RequestDestination::kIframe:
     case network::mojom::RequestDestination::kFrame:
     case network::mojom::RequestDestination::kFencedframe:
+    case network::mojom::RequestDestination::kWebIdentity:
       NOTREACHED();
       [[fallthrough]];