fixes #201, add support for custom URL mapping

lib/src/analysis_context.dart

 // Copyright (c) 2015, 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 dev_compiler.src.analysis_context;
 
 import 'package:analyzer/file_system/file_system.dart';
 import 'package:analyzer/file_system/memory_file_system.dart';
 import 'package:analyzer/src/generated/engine.dart';
 import 'package:analyzer/src/generated/java_io.dart' show JavaFile;
@@ skipping 16 matching lines @@
 /// `package:` URI resolvers.
 ///
 AnalysisContext createAnalysisContext(CompilerOptions options,
     {DartUriResolver sdkResolver, List fileResolvers}) {
   var context = _initContext(options);
 
   var sdkResolver = options.useMockSdk
       ? createMockSdkResolver(mockSdkSources)
       : createSdkPathResolver(options.dartSdkPath);
 
-  var resolvers = [sdkResolver];
+  var resolvers = [];
+  if (options.customUrlMappings.isNotEmpty) {
+    resolvers.add(new CustomUriResolver(options.customUrlMappings));
+  }
+  resolvers.add(sdkResolver);
   if (options.useImplicitHtml) {
     resolvers.add(_createImplicitEntryResolver(options));
   }
   if (fileResolvers == null) {
     fileResolvers = [new FileUriResolver()];
     fileResolvers.add(options.useMultiPackage
         ? new MultiPackageResolver(options.packagePaths)
         : new PackageUriResolver([new JavaFile(options.packageRoot)]));
   }
   resolvers.addAll(fileResolvers);
@@ skipping 34 matching lines @@
 
 /// Creates an analysis context that contains our restricted typing rules.
 AnalysisContext _initContext(ResolverOptions options) {
   var analysisOptions = new AnalysisOptionsImpl()..cacheSize = 512;
   AnalysisContextImpl res = AnalysisEngine.instance.createAnalysisContext();
   res.analysisOptions = analysisOptions;
   res.libraryResolverFactory =
       (context) => new LibraryResolverWithInference(context, options);
   return res;
 }