Extract ClosedWorldRefiner implementation from ClosedWorldImpl to ClosedWorldBase

tests/compiler/dart2js/memory_compiler.dart

 // Copyright (c) 2016, 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.test.memory_compiler;
 
 import 'dart:async';
 
 import 'package:compiler/compiler.dart' show DiagnosticHandler;
 import 'package:compiler/compiler_new.dart'
     show
         CompilationResult,
         CompilerDiagnostics,
         CompilerOutput,
         Diagnostic,
         PackagesDiscoveryProvider;
 import 'package:compiler/src/diagnostics/messages.dart' show Message;
-import 'package:compiler/src/elements/entities.dart' show LibraryEntity;
+import 'package:compiler/src/elements/entities.dart'
+    show LibraryEntity, MemberEntity;
 import 'package:compiler/src/enqueue.dart' show ResolutionEnqueuer;
 import 'package:compiler/src/null_compiler_output.dart' show NullCompilerOutput;
 import 'package:compiler/src/library_loader.dart' show LoadedLibraries;
 import 'package:compiler/src/options.dart' show CompilerOptions;
 
 import 'memory_source_file_helper.dart';
 
 export 'output_collector.dart';
 export 'package:compiler/compiler_new.dart' show CompilationResult;
 export 'diagnostic_helper.dart';
@@ skipping 147 matching lines @@
         libraryLoader.mapLibrary(library);
         copiedLibraries[library.canonicalUri] = library;
       }
     });
     compiler.processLoadedLibraries(new MemoryLoadedLibraries(copiedLibraries));
     ResolutionEnqueuer resolutionEnqueuer = compiler.startResolution();
 
     compiler.backend.constantCompilerTask
         .copyConstantValues(cachedCompiler.backend.constantCompilerTask);
 
-    Iterable cachedTreeElements =
+    Iterable<MemberEntity> cachedTreeElements =
         cachedCompiler.enqueuer.resolution.processedEntities;
-    cachedTreeElements.forEach((element) {
-      if (element.library.isPlatformLibrary) {
+    cachedTreeElements.forEach((MemberEntity element) {
+      if (element.library.canonicalUri.scheme == 'dart') {
         resolutionEnqueuer.registerProcessedElementInternal(element);
       }
     });
 
     // One potential problem that can occur when reusing elements is that there
     // is a stale reference to an old compiler object.  By nulling out the old
     // compiler's fields, such stale references are easier to identify.
     cachedCompiler.scanner = null;
     cachedCompiler.dietParser = null;
     cachedCompiler.parser = null;
@@ skipping 47 matching lines @@
       handler = (Uri uri, int begin, int end, String message, Diagnostic kind) {
         diagnosticHandler(uri, begin, end, message, kind);
         formattingHandler(uri, begin, end, message, kind);
       };
     }
   } else if (diagnosticHandler == null) {
     handler = (Uri uri, int begin, int end, String message, Diagnostic kind) {};
   }
   return handler;
 }