Only start http server for browser tests.

tools/test-runtime.dart

Index: tools/test-runtime.dart
diff --git a/tools/test-runtime.dart b/tools/test-runtime.dart
index b4a229fadeba18494ebbd5d133c88cb8ee9aa6fa..b9663ffe0cab54ad2933118a25332976f3ff5e89 100755
--- a/tools/test-runtime.dart
+++ b/tools/test-runtime.dart
@@ -92,7 +92,13 @@ main() {
   // Start global http server that serves the entire dart repo.
   // The http server is available on localhost:9876 for any
   // test that needs to load resources from the repo over http.
-  startHttpServer('127.0.0.1', 9876);
+  if (!listTests) {
+    // Only start the server if we are running browser tests.
+    var runningBrowserTests = configurations.some((config) {
+      return TestUtils.isBrowserRuntime(config['runtime']);
+    });
+    if (runningBrowserTests) startHttpServer('127.0.0.1', 9876);
+  }
 
   // Start process queue.
   new ProcessQueue(