Add ImportElement and ExportElement

pkg/compiler/lib/src/serialization/keys.dart

Index: pkg/compiler/lib/src/serialization/keys.dart
diff --git a/pkg/compiler/lib/src/serialization/keys.dart b/pkg/compiler/lib/src/serialization/keys.dart
index a3c276e84b8dd3bc5bb9a348dde723509b37e79b..de1af427ef6f6a103edcac0461fc0beccc35ec21 100644
--- a/pkg/compiler/lib/src/serialization/keys.dart
+++ b/pkg/compiler/lib/src/serialization/keys.dart
@@ -23,17 +23,21 @@ class Key {
   static const Key ELEMENT = const Key('element');
   static const Key ELEMENTS = const Key('elements');
   static const Key EXPORTS = const Key('exports');
+  static const Key EXPORT_SCOPE = const Key('export-scope');
   static const Key EXPRESSION = const Key('expression');
   static const Key FALSE = const Key('false');
   static const Key FIELD = const Key('field');
   static const Key FIELDS = const Key('fields');
   static const Key FUNCTION = const Key('function');
   static const Key ID = const Key('id');
+  static const Key IMPORT = const Key('import');
   static const Key IMPORTS = const Key('imports');
+  static const Key IMPORT_SCOPE = const Key('import-scope');
   static const Key INTERFACES = const Key('interfaces');
   static const Key INDEX = const Key('index');
   static const Key IS_ABSTRACT = const Key('isAbstract');
   static const Key IS_CONST = const Key('isConst');
+  static const Key IS_DEFERRED = const Key('isDeferred');
   static const Key IS_EXTERNAL = const Key('isExternal');
   static const Key IS_FINAL = const Key('isFinal');
   static const Key IS_NAMED = const Key('isNamed');
@@ -44,6 +48,7 @@ class Key {
   static const Key LEFT = const Key('left');
   static const Key LENGTH = const Key('length');
   static const Key LIBRARY = const Key('library');
+  static const Key LIBRARY_DEPENDENCY = const Key('library-dependency');
   static const Key LIBRARY_NAME = const Key('library-name');
   static const Key MEMBERS = const Key('members');
   static const Key NAME = const Key('name');
@@ -57,6 +62,7 @@ class Key {
       const Key('optional-parameter-types');
   static const Key PARAMETERS = const Key('parameters');
   static const Key PARAMETER_TYPES = const Key('parameter-types');
+  static const Key PREFIX = const Key('prefix');
   static const Key RETURN_TYPE = const Key('return-type');
   static const Key RIGHT = const Key('right');
   static const Key SUPERTYPE = const Key('supertype');