dart2js cps: Always use interceptors and type tags for 'is' checks.

pkg/compiler/lib/src/js_backend/codegen/unsugar.dart

Index: pkg/compiler/lib/src/js_backend/codegen/unsugar.dart
diff --git a/pkg/compiler/lib/src/js_backend/codegen/unsugar.dart b/pkg/compiler/lib/src/js_backend/codegen/unsugar.dart
index e0115f21c2e7102fb63b8c43a8f21d86937352c8..d740e9dba27e222309c8b1f399a4519a58bf899a 100644
--- a/pkg/compiler/lib/src/js_backend/codegen/unsugar.dart
+++ b/pkg/compiler/lib/src/js_backend/codegen/unsugar.dart
@@ -262,6 +262,18 @@ class UnsugarVisitor extends RecursiveVisitor {
     node.receiver = new Reference<Primitive>(newReceiver);
   }
 
+  processTypeOperator(TypeOperator node) {

[karlklose, 2015/05/22 07:40:49]

I think we should do this in the IR builder. Long term we should merge all of
the unsugar rewrites into the IR builder.

[asgerf, 2015/05/22 12:31:36]

I completely agree. There is a strange limbo in the time between building and
unsugaring where the IR doesn't seem to have clear semantics.

+    // Intercept the receiver to type operators.
+    // We don't have any type information here, so we use the set of all
+    // intercepted classes to be safe.
+    _glue.registerSpecializedGetInterceptor(_glue.interceptedClasses);
+    Primitive interceptor =
+        new Interceptor(node.receiver.definition, _glue.interceptedClasses);
+    insertLetPrim(interceptor, node);
+    node.receiver.unlink();
+    node.receiver = new Reference<Primitive>(interceptor);
+  }
+
   processInvokeMethodDirectly(InvokeMethodDirectly node) {
     if (_glue.isInterceptedMethod(node.target)) {
       Primitive nullPrim = nullConstant;