Fix analysis server integration tests on Windows.

pkg/analysis_server/test/integration/integration_tests.dart

Index: pkg/analysis_server/test/integration/integration_tests.dart
diff --git a/pkg/analysis_server/test/integration/integration_tests.dart b/pkg/analysis_server/test/integration/integration_tests.dart
index 4bd898cf6ddaf38f2ff29f488a7c914e2dcd0b13..a565119025715492857fc9af435e0aa7871a7721 100644
--- a/pkg/analysis_server/test/integration/integration_tests.dart
+++ b/pkg/analysis_server/test/integration/integration_tests.dart
@@ -508,7 +508,8 @@ class Server {
     // TODO(paulberry): move the logic for finding the script, the dart
     // executable, and the package root into a shell script.
     String dartBinary = Platform.executable;
-    String scriptDir = dirname(Platform.script.path);
+    String scriptDir = dirname(Platform.script.toFilePath(windows:
+        Platform.isWindows));
     String serverPath = normalize(join(scriptDir, '..', '..', 'bin',
         'server.dart'));
     List<String> arguments = [];