Hack around issue with is checks against type variables.

lib/compiler/implementation/ssa/builder.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 class Interceptors {
   Compiler compiler;
   Interceptors(Compiler this.compiler);
 
   SourceString mapOperatorToMethodName(Operator op) {
     String name = op.source.stringValue;
@@ skipping 1760 matching lines @@
       Node argument = node.arguments.head;
       TypeAnnotation typeAnnotation = argument.asTypeAnnotation();
       bool isNot = false;
       // TODO(ngeoffray): Duplicating pattern in resolver. We should
       // add a new kind of node.
       if (typeAnnotation == null) {
         typeAnnotation = argument.asSend().receiver;
         isNot = true;
       }
       Type type = elements.getType(typeAnnotation);
-      HInstruction instruction = new HIs(type, expression);
-      if (isNot) {
-        add(instruction);
-        instruction = new HNot(instruction);
+      if (type.element.kind === ElementKind.TYPE_VARIABLE) {
+        // TODO(karlklose): We emulate the frog behavior and answer
+        // true to any is check involving a type variable -- both is T
+        // and is !T -- until we have a proper implementation of
+        // reified generics.
+        stack.add(graph.addConstantBool(true));
+      } else {
+        HInstruction instruction = new HIs(type, expression);
+        if (isNot) {
+          add(instruction);
+          instruction = new HNot(instruction);
+        }
+        push(instruction);
       }
-      push(instruction);
     } else {
       visit(node.receiver);
       visit(node.argumentsNode);
       var right = pop();
       var left = pop();
       visitBinary(left, op, right);
     }
   }
 
   void addDynamicSendArgumentsToList(Send node, List<HInstruction> list) {
@@ skipping 1315 matching lines @@
                                         false,
                                         <HInstruction>[target, input]));
     return builder.pop();
   }
 
   HInstruction result() {
     flushLiterals();
     return prefix;
   }
 }