Handle relative paths in the output of "pub list-package-dirs".

pkg/analysis_server/test/resource_test.dart

Index: pkg/analysis_server/test/resource_test.dart
diff --git a/pkg/analysis_server/test/resource_test.dart b/pkg/analysis_server/test/resource_test.dart
index 409e0afd82954f4d8a807bd91d50eb6c404831a7..ec1a67d10e5a2c077038c0fa9c16faa2bf004221 100644
--- a/pkg/analysis_server/test/resource_test.dart
+++ b/pkg/analysis_server/test/resource_test.dart
@@ -329,6 +329,15 @@ main() {
         expect(parent2.path, equals('/'));
         expect(parent2.parent, isNull);
       });
+
+      test('canonicalizePath', () {
+        expect(folder.canonicalizePath('baz'), equals('/foo/bar/baz'));
+        expect(folder.canonicalizePath('/baz'), equals('/baz'));
+        expect(folder.canonicalizePath('../baz'), equals('/foo/baz'));
+        expect(folder.canonicalizePath('/a/b/../c'), equals('/a/c'));
+        expect(folder.canonicalizePath('./baz'), equals('/foo/bar/baz'));
+        expect(folder.canonicalizePath('/a/b/./c'), equals('/a/b/c'));
+      });
     });
 
     group('_MemoryFileSource', () {