[Fuchsia] Fix GN isolate map label for castrunner_browsertests.

TBR=jbudorick

Bug: 922635
Change-Id: Ie3d39b4ca2097a9a9e8061092e30394079c85260
Reviewed-on: https://chromium-review.googlesource.com/c/1423674
Reviewed-by: Wez <wez@chromium.org>
Commit-Queue: Wez <wez@chromium.org>
Auto-Submit: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#624446}
diff --git a/testing/buildbot/gn_isolate_map.pyl b/testing/buildbot/gn_isolate_map.pyl
index 1c3e2955b..2058182 100644
--- a/testing/buildbot/gn_isolate_map.pyl
+++ b/testing/buildbot/gn_isolate_map.pyl
@@ -412,7 +412,7 @@
     "type": "windowed_test_launcher",
   },
   "castrunner_browsertests": {
-    "label": "//webrunner:castrunner_browsertests",
+    "label": "//fuchsia:castrunner_browsertests",
     "type": "console_test_launcher",
   },
   "castrunner_integration_tests": {