Add support for resolving symbolic links

pkg/analyzer/test/file_system/memory_file_system_test.dart

Index: pkg/analyzer/test/file_system/memory_file_system_test.dart
diff --git a/pkg/analyzer/test/file_system/memory_file_system_test.dart b/pkg/analyzer/test/file_system/memory_file_system_test.dart
index 2ee57753d04e487af650dc33206b92091ed1d43f..58e06bf3b8c33a94a0067a20d9426166fae1125e 100644
--- a/pkg/analyzer/test/file_system/memory_file_system_test.dart
+++ b/pkg/analyzer/test/file_system/memory_file_system_test.dart
@@ -194,6 +194,11 @@ class FileTest {
     expect(file.exists, isTrue);
   }
 
+  void test_resolveSymbolicLinksSync() {
+    File file = provider.newFile('/test.txt', 'text');
+    expect(file.resolveSymbolicLinksSync(), file);
+  }
+
   void test_shortName() {
     File file = provider.getResource('/foo/bar/file.txt');
     expect(file.shortName, 'file.txt');