Improvement on future: add stack trace to unhandled failures.

tests/co19/co19-dart2js.status

 # 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.
 
 
 # Crashes first, please. Then untriaged bugs. There is a section below
 # for co19 bugs.
 [ $compiler == dart2js ]
 Language/11_Statements/05_For_A01_t07: Crash
 Language/03_Overview/1_Scoping_A02_t06: Fail # TODO(ahe): Please triage this failure.
@@ skipping 506 matching lines @@
 
 Language/10_Expressions/06_Lists_A07_t02: Fail # generic type information is lost during canonicalization.
 Language/10_Expressions/07_Maps_A06_t02: Fail # generic type information is lost during canonicalization.
 
 #
 # The following tests may be broken, but require further review.
 #
 [ $compiler == dart2js && $runtime == d8 ]
 LibTest/core/Expect/identical_A01_t01: Fail # TODO(floitsch): Is NaN identical to NaN?
 
+# Changed exception thrown by futures (co19 issue #269)
+LibTest/core/Completer/completeException_A01_t01: Fail, OK
+LibTest/core/Future/handleException_A01_t04: Fail, OK
+LibTest/core/Future/handleException_A01_t05: Fail, OK
+
 [ $compiler == dart2js && $browser ]
 *: Skip
 
 
 #
 # Missing compile-time errors.
 #
 [ $compiler == dart2js ]
 Language/05_Variables/05_Variables_A01_t04: Fail # Checks that a variable declaration cannot contain both 'final' and 'var'.
 Language/05_Variables/05_Variables_A01_t05: Fail # Checks that a variable declaration cannot contain both 'var' and 'type'.
@@ skipping 224 matching lines @@
 Language/14_Types/4_Interface_Types_A10_t01: Fail # http://dartbug.com/5020
 Language/14_Types/4_Interface_Types_A10_t02: Fail # http://dartbug.com/5020
 Language/14_Types/4_Interface_Types_A10_t03: Fail # http://dartbug.com/5020
 Language/14_Types/4_Interface_Types_A10_t04: Fail # http://dartbug.com/5020
 Language/14_Types/4_Interface_Types_A10_t07: Fail # http://dartbug.com/5020
 Language/14_Types/4_Interface_Types_A11_t02: Fail # http://dartbug.com/5020
 Language/14_Types/4_Interface_Types_A12_t09: Fail # http://dartbug.com/5020
 Language/14_Types/4_Interface_Types_A12_t10: Fail # http://dartbug.com/5020
 Language/14_Types/4_Interface_Types_A12_t14: Fail # http://dartbug.com/5020
 Language/14_Types/4_Interface_Types_A12_t16 :Fail # http://dartbug.com/5020