Add optional message to assert in Dart2js.

pkg/compiler/lib/src/resolution/registry.dart

Index: pkg/compiler/lib/src/resolution/registry.dart
diff --git a/pkg/compiler/lib/src/resolution/registry.dart b/pkg/compiler/lib/src/resolution/registry.dart
index 6a407543753e807d9561ac66e47eb0bde3902bd4..c4f7a193e81fb453cde5afa31638a0fdd8558d90 100644
--- a/pkg/compiler/lib/src/resolution/registry.dart
+++ b/pkg/compiler/lib/src/resolution/registry.dart
@@ -55,6 +55,11 @@ class EagerRegistry implements Registry {
   Iterable<Element> get otherDependencies => mapping.otherDependencies;
 
   @override
+  void registerAssert(bool hasMessage) {
+    // TODO(johnniwinther): Do something here?
+  }
+
+  @override
   void registerDependency(Element element) {
     mapping.registerDependency(element);
   }
@@ -583,13 +588,8 @@ class ResolutionRegistry implements Registry {
     world.registerInstantiatedType(type, this);
   }
 
-  void registerAssert(Send node) {
-    mapping.setAssert(node);
-    backend.resolutionCallbacks.onAssert(node, this);
-  }
-
-  bool isAssert(Send node) {
-    return mapping.isAssert(node);
+  void registerAssert(bool hasMessage) {
+    backend.resolutionCallbacks.onAssert(hasMessage, this);
   }
 
   void registerSendStructure(Send node, SendStructure sendStructure) {