Make WebKit Win10 part of win-ci.

BUG=790343

Change-Id: I64d509837aaf84043e1e3e749bcda748e0c42da4
Reviewed-on: https://chromium-review.googlesource.com/c/1260012Reviewed-by: Ryan Tseng <hinoka@chromium.org>
Commit-Queue: Jao-ke Chin-Lee <jchinlee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#596409}

infra/config/global/cr-buildbucket.cfg

@@ -2403,7 +2403,7 @@ buckets {
     builders {
       name: "WebKit Win10"
       dimensions: "os:Windows-10"
-      mixins: "webkit-ci"
+      mixins: "win-ci"
     }
     builders {
       name: "win32-dbg"