Convert analysis server over to use ContextBuilder

pkg/analyzer/lib/file_system/physical_file_system.dart

Index: pkg/analyzer/lib/file_system/physical_file_system.dart
diff --git a/pkg/analyzer/lib/file_system/physical_file_system.dart b/pkg/analyzer/lib/file_system/physical_file_system.dart
index b77114967a1ee5c91e87bf3bcb0034d0fdb1c3ed..38fc38affe90e0764e4b8d1467a0b28a3a4d2d4a 100644
--- a/pkg/analyzer/lib/file_system/physical_file_system.dart
+++ b/pkg/analyzer/lib/file_system/physical_file_system.dart
@@ -217,6 +217,11 @@ class _PhysicalFolder extends _PhysicalResource implements Folder {
   @override
   Stream<WatchEvent> get changes => new DirectoryWatcher(_entry.path).events;
 
+  /**
+   * Return the underlying file being represented by this wrapper.
+   */
+  io.Directory get _directory => _entry as io.Directory;
+
   @override
   String canonicalizePath(String relPath) {
     return normalize(join(path, relPath));
@@ -277,6 +282,16 @@ class _PhysicalFolder extends _PhysicalResource implements Folder {
   }
 
   @override
+  Folder resolveSymbolicLinksSync() {
+    try {
+      return new _PhysicalFolder(
+          new io.Directory(_directory.resolveSymbolicLinksSync()));
+    } on io.FileSystemException catch (exception) {
+      throw new FileSystemException(exception.path, exception.message);
+    }
+  }
+
+  @override
   Uri toUri() => new Uri.directory(path);
 }