Split RuntimesTypes into RuntimeTypes and RuntimeTypesEncoder

pkg/compiler/lib/src/js_backend/constant_emitter.dart

Index: pkg/compiler/lib/src/js_backend/constant_emitter.dart
diff --git a/pkg/compiler/lib/src/js_backend/constant_emitter.dart b/pkg/compiler/lib/src/js_backend/constant_emitter.dart
index f1d7f746648f26d509d55ad0b7afec80b8324dc8..46dc5884c8458d3c8136b0602cbe687023b03b0f 100644
--- a/pkg/compiler/lib/src/js_backend/constant_emitter.dart
+++ b/pkg/compiler/lib/src/js_backend/constant_emitter.dart
@@ -309,10 +309,10 @@ class ConstantEmitter
         !type.treatAsRaw &&
         backend.classNeedsRti(type.element)) {
       InterfaceType interface = type;
-      RuntimeTypes rti = backend.rti;
+      RuntimeTypesEncoder rtiEncoder = backend.rtiEncoder;
       Iterable<jsAst.Expression> arguments = interface.typeArguments
           .map((DartType type) =>
-              rti.getTypeRepresentationWithPlaceholders(type, (_){}));
+              rtiEncoder.getTypeRepresentationWithPlaceholders(type, (_){}));
       jsAst.Expression argumentList =
           new jsAst.ArrayInitializer(arguments.toList());
       return new jsAst.Call(getHelperProperty(backend.getSetRuntimeTypeInfo()),