fix embedder url mapping on Windows

pkg/analyzer/test/source/embedder_test.dart

Index: pkg/analyzer/test/source/embedder_test.dart
diff --git a/pkg/analyzer/test/source/embedder_test.dart b/pkg/analyzer/test/source/embedder_test.dart
index cb3186bbd17e517b47154685a53dffba2f4cef8e..9ee278e2ebc19173f232dc3fc83ed05cd9a706ac 100644
--- a/pkg/analyzer/test/source/embedder_test.dart
+++ b/pkg/analyzer/test/source/embedder_test.dart
@@ -104,7 +104,7 @@ main() {
         var source = sdk.fromFileUri(uri);
         expect(source, isNotNull, reason: filePath);
         expect(source.uri.toString(), dartUri);
-        expect(source.fullName, filePath);
+        expect(source.fullName, filePath.replaceAll('/', JavaFile.separator));
       }
 
       expectSource('/tmp/slippy.dart', 'dart:fox');