Added support for properly building and running isolates in recipes.

scripts/slave/recipes/gpu/build_and_test.py

Index: scripts/slave/recipes/gpu/build_and_test.py
diff --git a/scripts/slave/recipes/gpu/build_and_test.py b/scripts/slave/recipes/gpu/build_and_test.py
index 29257c39c39fb9059d08ea884c9876565dbbbb5f..adfe2653c2009fb6c67f644797fbb6177c1bef65 100644
--- a/scripts/slave/recipes/gpu/build_and_test.py
+++ b/scripts/slave/recipes/gpu/build_and_test.py
@@ -89,7 +89,12 @@ def GenTests(api):
   # Test one configuration skipping the compile.
   yield (
     api.test('mac_release_skip_compile') +
-    api.properties.git_scheduled(build_config='Release', skip_compile=True) +
+    api.properties.git_scheduled(
+      build_config='Release',
+      skip_compile=True,
+      # These would ordinarily be generated during the build step.
+      swarm_hashes=dict(
+        gl_tests='6e784864abbeeff7499c15f75b904851d633c187')) +
     api.platform.name('mac')
   )