[cr-buildbucket] Workaround for cores dimension

TBR=nodir@chromium.org

Bug: 731546
Change-Id: Iff90019d6c35a7fbaa60e73c46ccfe1c975a89c9
Reviewed-on: https://chromium-review.googlesource.com/1027110Reviewed-by: Sergey Berezin <sergeyberezin@chromium.org>
Commit-Queue: Sergey Berezin <sergeyberezin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553414}

infra/config/global/cr-buildbucket.cfg

@@ -1258,7 +1258,8 @@ buckets {
 
     builders { mixins: "ios-try" name: "ios-device" }
     builders { mixins: "ios-try" name: "ios-device-xcode-clang" }
-    builders { mixins: "ios-try" name: "ios-simulator" }
+    # TODO(crbug.com/836626): delete dimensions: "cores:" when bug is fixed.
+    builders { mixins: "ios-try" dimensions: "cores:" name: "ios-simulator" }
     builders { mixins: "ios-try" name: "ios-simulator-cronet" }
     builders { mixins: "ios-try" name: "ios-simulator-eg" }
     builders { mixins: "ios-try" name: "ios-simulator-xcode-clang" }