Avoid reparsing metadata expressions

pkg/compiler/lib/src/js_emitter/old_emitter/emitter.dart

 // Copyright (c) 2014, 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 OldEmitter implements Emitter {
   final Compiler compiler;
   final CodeEmitterTask task;
@@ skipping 647 matching lines @@
           [js(lazyInitializerName),
            js.string(namer.globalPropertyName(element)),
            js.string(namer.lazyInitializerName(element)),
            code,
            js.string(element.name)]);
     }
   }
 
   void emitMetadata(Program program, CodeOutput output, OutputUnit outputUnit) {
 
-    jsAst.Expression constructList(List<String> list) {
-      String listAsString = list == null ? '[]' : '[${list.join(",")}]';
-      return js.uncachedExpressionTemplate(listAsString).instantiate([]);
+    jsAst.Expression constructList(List<jsAst.Expression> list) {
+      return new jsAst.ArrayInitializer(list == null ? [] : list);
     }
 
-    List<String> types = program.metadataTypes[outputUnit];
+    List<jsAst.Expression> types = program.metadataTypes[outputUnit];
 
     if (outputUnit == compiler.deferredLoadTask.mainOutputUnit) {
       jsAst.Expression metadataAccess =
           generateEmbeddedGlobalAccess(embeddedNames.METADATA);
       jsAst.Expression typesAccess =
           generateEmbeddedGlobalAccess(embeddedNames.TYPES);
 
       output.addBuffer(
           jsAst.prettyPrint(new jsAst.Block([
               js.statement('# = #;', [metadataAccess,
@@ skipping 1257 matching lines @@
     for (Element element in compiler.enqueuer.codegen.newlyEnqueuedElements) {
       if (element.isInstanceMember) {
         cachedClassBuilders.remove(element.enclosingClass);
 
         nativeEmitter.cachedBuilders.remove(element.enclosingClass);
 
       }
     }
   }
 }