Make constant lists immutable.

tests/language/language-leg.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.
 
 [ $compiler == dart2js && $checked ]
 *: Skip
 
 
 [ $compiler == dart2js]
 AdjacentConstStringLiteralsTest: Pass # Not recognizing 'const' constructor call.
 CompileTimeConstant8Test: Fail # We don't take the generic type into account yet.
 
 
 # Compilation errors.
 CTConstTest: Fail # We don't take the generic type into account yet.
 CallOperatorTest: Fail # Unexpected token 'call'
 CharEscapeTest: Fail # Unhandled non-BMP character: U+10000
-ConstObjectsAreImmutableTest: Fail # Const objects are not immutable.
 Constructor6Test: Fail # Closures inside initializers not implemented.
 DefaultFactoryLibraryTest: Fail # lib is not a type
 DynamicTest: Fail # cannot resolve type F1
 Factory3Test: Fail # Handling of compile-time constants.
 FinalSyntaxTest/none: Fail # Incorrect compile-time constant handling.
 FunctionLiterals2Test: Fail # Closures inside initializers not implemented.
 FunctionSyntaxTest: Fail # Closures inside initializers not implemented.
 FunctionTypeAlias2Test: Fail # cannot resolve type f1
 FunctionTypeAlias3Test: Fail # cannot resolve type F
 FunctionTypeAlias4Test: Fail # cannot resolve type F
@@ skipping 179 matching lines @@
 
 
 RegExp3Test: Fail, OK # Expects exception from const constructor.
 
 
 ListTest: Fail, OK # Obsolete test uses List.copyFrom that was removed on 2011-10-31.
 
 
 [ $compiler == dart2js && $mode == release ]
 AssignTopMethodNegativeTest: Crash