Fix a bunch of pub tests that started running "pub get".

test/dart2js/environment_constant_test.dart

Index: test/dart2js/environment_constant_test.dart
diff --git a/test/dart2js/environment_constant_test.dart b/test/dart2js/environment_constant_test.dart
index 1128105a126c0327868a3fa973035369dafe6f61..117160655bff8367eee8496ae294117f9e9fc013 100644
--- a/test/dart2js/environment_constant_test.dart
+++ b/test/dart2js/environment_constant_test.dart
@@ -38,7 +38,7 @@ main() {
     });
 
     integration('from "pub serve"', () {
-      pubServe(args: ["--define", "name=fblthp"]);
+      pubServe(args: ["--define", "name=fblthp"], shouldGetFirst: true);
       requestShouldSucceed("file.dart.js", contains("fblthp"));
       endPubServe();
     });
@@ -53,7 +53,7 @@ main() {
         })
       ]).create();
 
-      pubServe(args: ["--define", "name=fblthp"]);
+      pubServe(args: ["--define", "name=fblthp"], shouldGetFirst: true);
       requestShouldSucceed("file.dart.js", allOf([
         contains("fblthp"),
         isNot(contains("slartibartfast"))