Implement @patch annotation for patch class members

runtime/bin/filter_patch.dart

Index: runtime/bin/filter_patch.dart
diff --git a/runtime/bin/filter_patch.dart b/runtime/bin/filter_patch.dart
index 11691e863553b1da47a73a4bdfbae420c4bd01b9..db086f9a6b9141733078f00c277ec6e56ea07cb4 100644
--- a/runtime/bin/filter_patch.dart
+++ b/runtime/bin/filter_patch.dart
@@ -29,14 +29,14 @@ class _ZLibDeflateFilter extends _FilterImpl {
 }
 
 @patch class _Filter {
-  /* @patch */ static _Filter _newZLibDeflateFilter(bool gzip, int level,
+  @patch static _Filter _newZLibDeflateFilter(bool gzip, int level,
                                                     int windowBits, int memLevel,
                                                     int strategy,
                                                     List<int> dictionary,
                                                     bool raw) =>
       new _ZLibDeflateFilter(gzip, level, windowBits, memLevel, strategy,
                              dictionary, raw);
-  /* @patch */ static _Filter _newZLibInflateFilter(int windowBits,
+  @patch static _Filter _newZLibInflateFilter(int windowBits,
                                                     List<int> dictionary,
                                                     bool raw) =>
       new _ZLibInflateFilter(windowBits, dictionary, raw);