dart2js: add type arguments to constructor in case the class needs rti.

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

Index: pkg/compiler/lib/src/js_emitter/class_stub_generator.dart
diff --git a/pkg/compiler/lib/src/js_emitter/class_stub_generator.dart b/pkg/compiler/lib/src/js_emitter/class_stub_generator.dart
index aef381f2c88d1bc67b31354f4e521bfde8703691..935c275ec72c08adfc85b8eaf2c213f640ebcdf4 100644
--- a/pkg/compiler/lib/src/js_emitter/class_stub_generator.dart
+++ b/pkg/compiler/lib/src/js_emitter/class_stub_generator.dart
@@ -20,10 +20,14 @@ class ClassStubGenerator {
     //        [ constructorName, fields,
     //            fields.map(
     //                (name) => js('this.# = #', [name, name]))]));
-    return js('function(#) { #; this.#();}',
-        [fields,
-         fields.map((name) => js('this.# = #', [name, name])),
-         namer.deferredAction]);
+    return js('''function(#, typeInfo) {
+                   #;
+                   if (typeInfo) this.\$builtinTypeInfo = typeInfo;

[herhut, 2015/04/20 10:24:29]

Why not set this unconditionally? Then the instances with and without typeInfo
will get the same map and the value is still undefined if no typeinfo was
provided....

[zarah, 2015/04/20 12:34:50]

There is code depending on whether or not that property is there, so, as
discussed, leaving it for now and added a todo.

+                   this.#();
+                 }''',
+              [fields,
+               fields.map((name) => js('this.# = #', [name, name])),
+               namer.deferredAction]);
   }
 
   jsAst.Expression generateGetter(Element member, String fieldName) {