infra: allow V8 to use Chromium's -dev pool.

R=bpastene, liviurau, machenbach

Bug: 1142484
Change-Id: Id121d0fb153a2a7de3c2fab5f432d0083e841dc3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2589032
Auto-Submit: Andrii Shyshkalov <tandrii@google.com>
Commit-Queue: Garrett Beaty <gbeaty@chromium.org>
Reviewed-by: Garrett Beaty <gbeaty@chromium.org>
Cr-Commit-Position: refs/heads/master@{#836623}

infra/config/dev/swarming.star

@@ -18,6 +18,7 @@ swarming.pool_realm(
     projects = [
         "infra",
         "infra-experimental",
+        "v8",
     ],
 )
 

infra/config/generated/realms-dev.cfg

@@ -73,6 +73,7 @@ realms {
     role: "role/swarming.poolUser"
     principals: "project:infra"
     principals: "project:infra-experimental"
+    principals: "project:v8"
   }
 }
 realms {