Add source mappings and inlined Dart code to diff_view.

tests/compiler/dart2js/sourcemaps/sourcemap_helper.dart

Index: tests/compiler/dart2js/sourcemaps/sourcemap_helper.dart
diff --git a/tests/compiler/dart2js/sourcemaps/sourcemap_helper.dart b/tests/compiler/dart2js/sourcemaps/sourcemap_helper.dart
index 019e8be34279a6942a863e54cb01f8c59757d192..73bc194a0e963af4379e719c84f568898ef9affc 100644
--- a/tests/compiler/dart2js/sourcemaps/sourcemap_helper.dart
+++ b/tests/compiler/dart2js/sourcemaps/sourcemap_helper.dart
@@ -388,17 +388,22 @@ class SourceMapProcessor {
     }
 
     return new SourceMaps(
-        sourceFileManager, mainSourceMapInfo, elementSourceMapInfos);
+        compiler,
+        sourceFileManager,
+        mainSourceMapInfo,
+        elementSourceMapInfos);
   }
 }
 
 class SourceMaps {
+  final api.CompilerImpl compiler;
   final SourceFileManager sourceFileManager;
   // TODO(johnniwinther): Supported multiple output units.
   final SourceMapInfo mainSourceMapInfo;
   final Map<Element, SourceMapInfo> elementSourceMapInfos;
 
   SourceMaps(
+      this.compiler,
       this.sourceFileManager,
       this.mainSourceMapInfo,
           this.elementSourceMapInfos);