dart2js: store typeToInterceptorMap in the model.

pkg/compiler/lib/src/js_emitter/program_builder.dart

Index: pkg/compiler/lib/src/js_emitter/program_builder.dart
diff --git a/pkg/compiler/lib/src/js_emitter/program_builder.dart b/pkg/compiler/lib/src/js_emitter/program_builder.dart
index 5b35217ce4b63c2959a8933e4db29f9afc7afc9e..0f1f7ee778973a896c8a8e0b66b05599d37e9e05 100644
--- a/pkg/compiler/lib/src/js_emitter/program_builder.dart
+++ b/pkg/compiler/lib/src/js_emitter/program_builder.dart
@@ -118,6 +118,7 @@ class ProgramBuilder {
     return new Program(
         outputs,
         _buildLoadMap(),
+        _buildTypeToInterceptorMap(),
         outputContainsNativeClasses: containsNativeClasses,
         outputContainsConstantList: _task.outputContainsConstantList);
   }
@@ -138,6 +139,12 @@ class ProgramBuilder {
     return loadMap;
   }
 
+  js.Expression _buildTypeToInterceptorMap() {
+    InterceptorStubGenerator stubGenerator =
+        new InterceptorStubGenerator(_compiler, namer, backend);
+    return stubGenerator.generateTypeToInterceptorMap();
+  }
+
   MainFragment _buildMainOutput(LibrariesMap librariesMap) {
     // Construct the main output from the libraries and the registered holders.
     MainFragment result = new MainFragment(