[pkg:test_runner] Replace space from test config name

https://dart-review.googlesource.com/c/sdk/+/181404 disallows spaces
in Configurations.

Change-Id: I0582eca064bd6d88ebcbbf411e44a6147895148c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/184902
Auto-Submit: Srujan Gaddam <srujzs@google.com>
Commit-Queue: William Hesse <whesse@google.com>
Reviewed-by: William Hesse <whesse@google.com>
diff --git a/pkg/test_runner/bin/launch_browser.dart b/pkg/test_runner/bin/launch_browser.dart
index 1924521..a92be18 100644
--- a/pkg/test_runner/bin/launch_browser.dart
+++ b/pkg/test_runner/bin/launch_browser.dart
@@ -34,7 +34,7 @@
   var runtime = Runtime.find(name);
   var configuration = TestConfiguration(
       configuration: Configuration(
-          "dummy configuration", null, null, null, runtime, null));
+          "dummy-configuration", null, null, null, runtime, null));
   var executable = configuration.browserLocation;
   var browser = Browser.byRuntime(runtime, executable);
   browser.start(arguments[1]);