Fix frog build: exclude DuplicateImplementsTest

tests/language/language.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.
 
 # This directory contains tests that are intended to show the
 # current state of the language.
 
 # In order to maintain maximum test coverage for all builds,
 # please use the following procedure to mark a test
 # failed on architectures other than the one you are working on.
@@ skipping 187 matching lines @@
 
 [ $component == frogsh ||  $component == frog || ($component == webdriver && ($browser == chrome || $browser == ff || $browser == safari)) || $component == frogium ]
 Factory3Test: Fail # Issue 417
 CallThroughNullGetterTest: Fail # Throw ObjectNotClosure instead of NullPointerException.
 ExtendTypeParameterNegativeTest: Skip # Issue 886
 ExtendTypeParameter2NegativeTest: Skip # Issue 886
 ImplementTypeParameterNegativeTest: Skip # Issue 887
 FactoryImplementationTest: Fail # Issue 523
 PseudoKWTest: Fail  # Issue 356
 NamingTest: Fail    # Issue 356
+DuplicateImplementsTest: Fail   # Issue 976
 
 # VM or DartC specific tests not to be run by Frog. See language.status
 *VMTest: Skip
 *VMNegativeTest: Skip
 *DartcTest: Skip
 *DartcNegativeTest: Skip
 # Currently, these patterns skip three tests:
 # MathVMTest - correctly skipped as this relies on VM guarantees
 #    - should add a version of this with the --enable_type_checks flag
 # TypeVMTest - correctly skipped as this relies on detailed of TypeError
@@ skipping 147 matching lines @@
 # these tests are inconsistent in frogium and frogsh-node, investigate
 StaticField1RunNegativeTest: Pass # but error is not correct
 StaticField2RunNegativeTest: Pass # but error is not correct
 
 
 [ $arch == simarm ]
 *: Skip
 
 [ $arch == arm ]
 *: Skip