Add deferred map info to dump-info.

pkg/compiler/lib/src/dump_info.dart

Index: pkg/compiler/lib/src/dump_info.dart
diff --git a/pkg/compiler/lib/src/dump_info.dart b/pkg/compiler/lib/src/dump_info.dart
index b2442b911157e36f8f31120342e2c09a77ccf7f3..c92ea25f36065b638010032b889b5239753d0449 100644
--- a/pkg/compiler/lib/src/dump_info.dart
+++ b/pkg/compiler/lib/src/dump_info.dart
@@ -639,6 +639,10 @@ class DumpInfoTask extends CompilerTask {
       'holding': holding,
       'outputUnits': outputUnits,
       'dump_version': 3,
+      'deferredFiles': compiler.deferredLoadTask.computeDeferredMap(),
+      // This increases when new information is added to the map, but the viewer
+      // still is compatible.
+      'dump_minor_version': '1'
     };
 
     Duration toJsonDuration = new DateTime.now().difference(startToJsonTime);