Work in progress: front end hot reload API

pkg/kernel/lib/analyzer/loader.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 kernel.analyzer.loader;
 
 import 'dart:async';
 import 'dart:io' as io;
 
 import 'package:analyzer/analyzer.dart';
 import 'package:analyzer/file_system/file_system.dart';
@@ skipping 90 matching lines @@
 
   /// Classes that have been referenced, and must be promoted to type level
   /// so as not to expose partially initialized classes.
   final List<ast.Class> temporaryClassWorklist = [];
 
   LibraryElement _libraryBeingLoaded = null;
 
   bool get strongMode => context.analysisOptions.strongMode;
 
   DartLoader(this.repository, DartOptions options, Packages packages,
-      {DartSdk dartSdk})
-      : this.context = createContext(options, packages, dartSdk: dartSdk),
+      {DartSdk dartSdk, AnalysisContext context})
+      : this.context = context ?? createContext(options, packages, dartSdk: dartSdk),
         this.applicationRoot = options.applicationRoot;
 
   String getLibraryName(LibraryElement element) {
     return element.name.isEmpty ? null : element.name;
   }
 
   ast.Library getLibraryReference(LibraryElement element) {
     var uri = applicationRoot.relativeUri(element.source.uri);
     return repository.getLibraryReference(uri)
       ..name ??= getLibraryName(element)
@@ skipping 744 matching lines @@
   AnalysisContext context = AnalysisEngine.instance.createAnalysisContext()
     ..sourceFactory = new SourceFactory(resolvers)
     ..analysisOptions = createAnalysisOptions(options.strongMode);
 
   options.declaredVariables.forEach((String name, String value) {
     context.declaredVariables.define(name, value);
   });
 
   return context;
 }