Adds more BUILD.gns to ash

ash/test/ash_test_environment.h

Index: ash/test/ash_test_environment.h
diff --git a/ash/test/ash_test_environment.h b/ash/test/ash_test_environment.h
index c533120f7b3a64bb74c2df07455e75dfef2692ab..ebd9e9a28883abe152604f0243d817b1e1b1ed46 100644
--- a/ash/test/ash_test_environment.h
+++ b/ash/test/ash_test_environment.h
@@ -25,9 +25,9 @@ namespace test {
 //
 // AshTestBase creates an AshTestEnvironment by way of
 // AshTestEnvironment::Create(). The implementation of Create() depends upon
-// the ash target that was linked against: //ash:test_support_with_content
-// includes AshTestEnvironmentContent and //ash:test_support_without_content
-// includes AshTestEnvironmentDefault.
+// the ash target that was linked against: //ash/test:test_support_with_content
+// includes AshTestEnvironmentContent and
+// //ash/test:test_support_without_content includes AshTestEnvironmentDefault.
 class AshTestEnvironment {
  public:
   virtual ~AshTestEnvironment() {}