Address the remaining review comments on http://chromiumcodereview.appspot.com/9431029.

lib/compiler/implementation/ssa/codegen.dart

Index: lib/compiler/implementation/ssa/codegen.dart
diff --git a/lib/compiler/implementation/ssa/codegen.dart b/lib/compiler/implementation/ssa/codegen.dart
index 67774ca552f11613bb09748c48bc90608e9c06e8..45467c78bdab7dda46e6385a724fd57e6f87d58c 100644
--- a/lib/compiler/implementation/ssa/codegen.dart
+++ b/lib/compiler/implementation/ssa/codegen.dart
@@ -1485,12 +1485,12 @@ class SsaCodeGenerator implements HVisitor {
   }
 
   void visitIs(HIs node) {
-    Type type = node.typeName;
+    Type type = node.typeExpression;
     Element element = type.element;
     if (element.kind === ElementKind.TYPE_VARIABLE) {
-      compiler.unimplemented("visitIs for type variables");
+      compiler.unimplemented("visitIs for type variables", instruction: node);
     } else if (element.kind === ElementKind.TYPEDEF) {
-      compiler.unimplemented("visitIs for typedefs");
+      compiler.unimplemented("visitIs for typedefs", instruction: node);
     }
     compiler.registerIsCheck(element);
     LibraryElement coreLibrary = compiler.coreLibrary;