Factor out some common logic from the launchers.

test/runner/browser/internet_explorer_test.dart

Index: test/runner/browser/internet_explorer_test.dart
diff --git a/test/runner/browser/internet_explorer_test.dart b/test/runner/browser/internet_explorer_test.dart
index e90d1c58692253c5d6fa0f3cc8224a763942ac35..024699186968398cc4572f149d8d0b1f77490fa3 100644
--- a/test/runner/browser/internet_explorer_test.dart
+++ b/test/runner/browser/internet_explorer_test.dart
@@ -103,6 +103,6 @@ webSocket.addEventListener("open", function() {
     var ie = new InternetExplorer("http://dart-lang.org",
         executable: "_does_not_exist");
     expect(ie.onExit, throwsA(isApplicationException(startsWith(
-        "Failed to start Internet Explorer: $noSuchFileMessage"))));
+        "Failed to run Internet Explorer: $noSuchFileMessage"))));
   });
 }