Add Dart code to diff_view

pkg/compiler/lib/src/io/source_information.dart

Index: pkg/compiler/lib/src/io/source_information.dart
diff --git a/pkg/compiler/lib/src/io/source_information.dart b/pkg/compiler/lib/src/io/source_information.dart
index 0138b41701689e3dfc03c317f9bc5f31f1a1213b..da46d43b5a823a86b92206978f3d4e9d3e46994e 100644
--- a/pkg/compiler/lib/src/io/source_information.dart
+++ b/pkg/compiler/lib/src/io/source_information.dart
@@ -104,6 +104,10 @@ class SourceInformationBuilder {
 
   /// 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.