dart2js: split out types from metadata.

pkg/compiler/lib/src/js_emitter/metadata_collector.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart2js.js_emitter;
 
 class MetadataCollector {
   final Compiler _compiler;
   final Emitter _emitter;
 
   /// A list of JS expressions that represent metadata, parameter names and
-  /// type, and return types.
-  final List<String> globalMetadata = [];
+  /// type variable types.
+  final List<String> globalMetadata = <String>[];
 
   /// A map used to canonicalize the entries of globalMetadata.
   final Map<String, int> _globalMetadataMap = <String, int>{};
 
+  /// A list of JS expression representing types including function types and
+  /// typedefs.
+  final List<String> types = <String>[];
+
+  /// A map used to canonicalize the entries of types.
+  final Map<String, int> _typesMap = <String, int>{};
+
   MetadataCollector(this._compiler, this._emitter);
 
   JavaScriptBackend get _backend => _compiler.backend;
   TypeVariableHandler get _typeVariableHandler => _backend.typeVariableHandler;
 
   bool _mustEmitMetadataFor(Element element) {
     return _backend.mustRetainMetadata &&
         _backend.referencedFromMirrorSystem(element);
   }
 
@@ skipping 61 matching lines @@
             type,
             (variable) {
               return js.number(
                   _typeVariableHandler.reifyTypeVariable(
                       variable.element));
             },
             (TypedefType typedef) {
               return _backend.isAccessibleByReflection(typedef.element);
             });
 
-    return addGlobalMetadata(
+    return addType(
         jsAst.prettyPrint(representation, _compiler).getText());
   }
 
   int reifyName(String name) {
     return addGlobalMetadata('"$name"');
   }
 
   int addGlobalMetadata(String string) {
     return _globalMetadataMap.putIfAbsent(string, () {
       globalMetadata.add(string);
       return globalMetadata.length - 1;
     });
   }
 
+  int addType(String compiledType) {
+    return _typesMap.putIfAbsent(compiledType, () {
+      types.add(compiledType);
+      return types.length - 1;
+    });
+  }
+
   List<int> computeMetadata(FunctionElement element) {
     return _compiler.withCurrentElement(element, () {
       if (!_mustEmitMetadataFor(element)) return const <int>[];
       List<int> metadata = <int>[];
       Link link = element.metadata;
       // TODO(ahe): Why is metadata sometimes null?
       if (link != null) {
         for (; !link.isEmpty; link = link.tail) {
           metadata.add(reifyMetadata(link.head));
         }
       }
       return metadata;
     });
   }
 }