Revert "Delay Firefox browser startup in test scripts, to flatten load."

tools/testing/dart/browser_controller.dart

Index: tools/testing/dart/browser_controller.dart
diff --git a/tools/testing/dart/browser_controller.dart b/tools/testing/dart/browser_controller.dart
index 7e0b0dfc4b5319b189e4f897456878f8768c575e..27765697ea3b74db45fe86f46381cd51199c2df6 100644
--- a/tools/testing/dart/browser_controller.dart
+++ b/tools/testing/dart/browser_controller.dart
@@ -767,10 +767,7 @@ class Firefox extends Browser {
         ];
         var environment = new Map<String, String>.from(Platform.environment);
         environment["MOZ_CRASHREPORTER_DISABLE"] = "1";
-        // TODO(26060): Remove delay when dart2js stops hanging under load.
-        return new Future.delayed(new Duration(seconds: 10)).then((_) {
-          return startBrowserProcess(_binary, args, environment: environment);
-        });
+        return startBrowserProcess(_binary, args, environment: environment);
       });
     }).catchError((e) {
       _logEvent("Running $_binary --version failed with $e");