Add Dart code to diff_view

pkg/compiler/lib/src/io/source_information.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 dart2js.source_information;
 
 import '../common.dart';
 import '../elements/elements.dart' show
     AstElement,
     LocalElement;
@@ skipping 86 matching lines @@
   SourceInformation buildIf(Node node) => null;
 
   /// Generate [SourceInformation] for the constructor invocation in [node].
   SourceInformation buildNew(Node node) => null;
 
   /// Generate [SourceInformation] for the throw in [node].
   SourceInformation buildThrow(Node node) => null;
 
   /// Generate [SourceInformation] for the assignment in [node].
   SourceInformation buildAssignment(Node node) => null;
+
+  /// Generate [SourceInformation] for the variable declaration inserted as
+  /// first statement of a function.
+  SourceInformation buildVariableDeclaration() => null;
 }
 
 /// A location in a source file.
 abstract class SourceLocation {
   final SourceFile _sourceFile;
   int _line;
 
   SourceLocation(this._sourceFile) {
     assert(isValid);
   }
@@ skipping 81 matching lines @@
     return '${computeElementNameForSourceMaps(local.executableContext)}.$name';
   } else if (element.enclosingClass != null) {
     if (element.enclosingClass.isClosure) {
       return computeElementNameForSourceMaps(element.enclosingClass);
     }
     return '${element.enclosingClass.name}.${element.name}';
   } else {
     return element.name;
   }
 }