Don't implicitly run "pub get".

test/dart2js/unminified_in_nonrelease_mode_test.dart

Index: test/dart2js/unminified_in_nonrelease_mode_test.dart
diff --git a/test/dart2js/unminified_in_nonrelease_mode_test.dart b/test/dart2js/unminified_in_nonrelease_mode_test.dart
index ef8187c9cf6876baa9cde4d339440ab2d5c5072f..81702e74b203ce3d2c7b09cbe4381af0a15e5bb3 100644
--- a/test/dart2js/unminified_in_nonrelease_mode_test.dart
+++ b/test/dart2js/unminified_in_nonrelease_mode_test.dart
@@ -15,7 +15,8 @@ main() {
       ])
     ]).create();
 
-    pubServe(args: ["--mode", "whatever"], shouldGetFirst: true);
+    pubGet();
+    pubServe(args: ["--mode", "whatever"]);
     requestShouldSucceed("main.dart.js", isUnminifiedDart2JSOutput);
     endPubServe();
   });