Connect analyzer's AnalysisError object to front_end's CompilationError.

pkg/front_end/lib/src/base/source.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.
 
 import 'package:front_end/src/base/analysis_target.dart';
 import 'package:front_end/src/base/timestamped_data.dart';
 import 'package:front_end/src/base/uri_kind.dart';
+import 'package:source_span/source_span.dart' as source_span;
 
 /**
  * The interface `Source` defines the behavior of objects representing source code that can be
  * analyzed by the analysis engine.
  *
  * Implementations of this interface need to be aware of some assumptions made by the analysis
  * engine concerning sources:
  * * Sources are not required to be unique. That is, there can be multiple instances representing
  * the same source.
  * * Sources are long lived. That is, the engine is allowed to hold on to a source for an extended
@@ skipping 82 matching lines @@
    * example, for a source representing a file this would typically be the name of the file.
    *
    * @return a name that can be displayed to the user to denote this source
    */
   String get shortName;
 
   @override
   Source get source => this;
 
   /**
+   * Return the [source_span.SourceFile] object corresponding to this source.
+   */
+  source_span.SourceFile get sourceFile;
+
+  /**
    * Return the URI from which this source was originally derived.
    *
    * @return the URI from which this source was originally derived
    */
   Uri get uri;
 
   /**
    * Return the kind of URI from which this source was originally derived. If this source was
    * created from an absolute URI, then the returned kind will reflect the scheme of the absolute
    * URI. If it was created from a relative URI, then the returned kind will be the same as the kind
@@ skipping 19 matching lines @@
    * Return `true` if this source exists.
    *
    * Clients should consider using the method [AnalysisContext.exists] because
    * contexts can have local overrides of the content of a source that the source is not aware of
    * and a source with local content is considered to exist even if there is no file on disk.
    *
    * @return `true` if this source exists
    */
   bool exists();
 }