Add MultiSourceInformationStrategy

tests/compiler/dart2js/sourcemaps/js_tracer.dart

Index: tests/compiler/dart2js/sourcemaps/js_tracer.dart
diff --git a/tests/compiler/dart2js/sourcemaps/js_tracer.dart b/tests/compiler/dart2js/sourcemaps/js_tracer.dart
index 6901e402404f36c547a31c40a5ceeb1a1ea2d29c..aacf1c6fc9361314f031f4f95c1f05400bd1c6f4 100644
--- a/tests/compiler/dart2js/sourcemaps/js_tracer.dart
+++ b/tests/compiler/dart2js/sourcemaps/js_tracer.dart
@@ -7,6 +7,7 @@ library sourcemap.js_tracer;
 import 'package:compiler/src/io/source_information.dart';
 import 'package:compiler/src/io/position_information.dart';
 import 'package:compiler/src/js/js.dart' as js;
+import 'package:compiler/src/js/js_source_mapping.dart';
 import 'sourcemap_helper.dart';
 import 'trace_graph.dart';
 
@@ -17,7 +18,10 @@ TraceGraph createTraceGraph(SourceMapInfo info, Coverage coverage) {
   CodePositionMap codePositions =
       new CodePositionCoverage(info.jsCodePositions, coverage);
   JavaScriptTracer tracer = new JavaScriptTracer(
-      codePositions, [new CoverageListener(coverage), listener]);
+      codePositions, const SourceInformationReader(), [
+    new CoverageListener(coverage, const SourceInformationReader()),
+    listener
+  ]);
   info.node.accept(tracer);
   return graph;
 }
@@ -29,6 +33,8 @@ class StepTraceListener extends TraceListener
 
   StepTraceListener(this.graph);
 
+  SourceInformationReader get reader => const SourceInformationReader();
+
   @override
   void onStep(js.Node node, Offset offset, StepKind kind) {
     SourceInformation sourceInformation = computeSourceInformation(node);