Split MirrorsData methods and MirrorsDataImpl data by element kind.

pkg/compiler/lib/src/js_emitter/full_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.
 
 library dart2js.js_emitter.full_emitter;
 
 import 'dart:collection' show HashMap;
 import 'dart:convert';
 
 import 'package:js_runtime/shared/embedded_names.dart' as embeddedNames;
@@ skipping 1029 matching lines @@
         uri =
             relativize(compiler.options.outputUri, library.canonicalUri, false);
       }
     }
 
     String libraryName = (!compiler.options.enableMinification ||
             backend.mirrorsData.mustRetainLibraryNames)
         ? library.libraryName
         : "";
 
-    jsAst.Fun metadata = task.metadataCollector.buildMetadataFunction(library);
+    jsAst.Fun metadata =
+        task.metadataCollector.buildLibraryMetadataFunction(library);
 
     ClassBuilder descriptor = elementDescriptors[fragment][library];
 
     jsAst.ObjectInitializer initializer;
     if (descriptor == null) {
       // Nothing of the library was emitted.
       // TODO(floitsch): this should not happen. We currently have an example
       // with language/prefix6_negative_test.dart where we have an instance
       // method without its corresponding class.
       initializer = new jsAst.ObjectInitializer([]);
@@ skipping 867 matching lines @@
     // data.
     mapping["_comment"] = "This mapping shows which compiled `.js` files are "
         "needed for a given deferred library import.";
     mapping.addAll(compiler.deferredLoadTask.computeDeferredMap());
     compiler.outputProvider(
         compiler.options.deferredMapUri.path, '', OutputType.info)
       ..add(const JsonEncoder.withIndent("  ").convert(mapping))
       ..close();
   }
 }