Hack around issue with is checks against type variables.

tests/co19/co19-leg.status

 # Copyright (c) 2011, 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.
 
 [ $compiler == dart2js && $system == macos && $runtime == d8 ]
 LibTest/core/Math/acos_A01_t01: Fail, OK
 LibTest/core/Math/asin_A01_t01: Fail, OK
 LibTest/core/Math/atan_A01_t01: Fail, OK
 
 
@@ skipping 118 matching lines @@
 #
 [ $compiler == dart2js ]
 Language/06_Functions/2_Formal_Parameters/2_Named_Optional_Formals_A01_t01: Fail # compiler cancelled: internal error: expected expected optional parameters
 Language/07_Classes/1_Instance_Methods/2_Operators_A01_t01: Fail # compiler cancelled: unexpected token 'call'
 Language/07_Classes/1_Instance_Methods/2_Operators_A07_t05: Fail # compiler cancelled: unexpected token 'call'
 Language/07_Classes/5_Constructors/1_Generative_Constructors_A13_t01: Fail # compiler cancelled: cannot resolve type T
 Language/07_Classes/5_Constructors/2_Factories_A01_t01: Fail # compiler cancelled: cannot find constructor A or ADef
 Language/07_Classes/8_Superclasses/1_Inheritance_and_Overriding_A02_t03: Fail # compiler cancelled: internal error: super property store not implemented
 Language/08_Interfaces/4_Superinterfaces/1_Inheritance_and_Overriding_A01_t02: Fail # compiler cancelled: no method named foo in class I
 Language/09_Generics/09_Generics_A04_t03: Fail # compiler cancelled: cannot resolve type N
-Language/09_Generics/09_Generics_A04_t04: Fail # compiler cancelled: cannot resolve type T
 Language/11_Statements/13_Continue_A02_t12: Fail # compiler cancelled: cannot resolve label L
 Language/11_Statements/13_Continue_A02_t13: Fail # compiler cancelled: cannot resolve label L
 Language/13_Types/2_Dynamic_Type_System_A02_t01: Fail # compiler cancelled: cannot resolve type MalformedType
-Language/13_Types/4_Interface_Types_A05_t04: Fail # compiler cancelled: cannot resolve type T
-Language/13_Types/4_Interface_Types_A08_t01: Fail # compiler cancelled: cannot resolve type S
 Language/13_Types/5_Function_Types_A02_t01: Fail # compiler cancelled: unexpected token 'call'
-Language/13_Types/6_Type_Dynamic_A02_t01: Fail # compiler cancelled: cannot resolve type S
 Language/13_Types/3_Type_Declarations/1_Typedef_A06_t01: Pass # internal error: visitIs for typedefs not implemented
 Language/13_Types/3_Type_Declarations/1_Typedef_A06_t02: Pass # internal error: visitIs for typedefs not implemented
 Language/13_Types/3_Type_Declarations/1_Typedef_A06_t03: Pass # internal error: visitIs for typedefs not implemented
 Language/13_Types/3_Type_Declarations/1_Typedef_A06_t04: Pass # internal error: visitIs for typedefs not implemented
 
 
 Language/03_Overview/1_Scoping_A02_t07: Fail # duplicate definition of f(var f){f();}
 Language/03_Overview/1_Scoping_A02_t12: Fail # duplicate definition of x=42
 Language/03_Overview/1_Scoping_A02_t13: Fail # duplicate definition of x=0
 Language/03_Overview/2_Privacy_A01_t06: Fail # cannot resolve type _inaccessibleFuncType
@@ skipping 347 matching lines @@
 Language/12_Libraries_and_Scripts/12_Libraries_and_Scripts_A05_t03: Fail, OK # @compile-error
 Language/12_Libraries_and_Scripts/12_Libraries_and_Scripts_A07_t02: Fail, OK # @compile-error
 Language/12_Libraries_and_Scripts/1_Imports_A03_t05: Fail, OK # @compile-error
 Language/12_Libraries_and_Scripts/1_Imports_A05_t01: Fail, OK # @compile-error
 Language/12_Libraries_and_Scripts/1_Imports_A07_t01: Fail, OK # @compile-error
 Language/12_Libraries_and_Scripts/1_Imports_A07_t02: Fail, OK # @compile-error
 Language/12_Libraries_and_Scripts/2_Includes_A01_t01: Fail, OK # @compile-error
 Language/12_Libraries_and_Scripts/2_Includes_A03_t03: Fail, OK # @compile-error
 Language/13_Types/1_Static_Types_A02_t08: Fail, OK # @compile-error
 Language/13_Types/7_Type_Void_A01_t02: Fail, OK # @compile-error