Also create abstract fields for top-level getters and setters.

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.
 
 [ $component == leg && $checked ]
 *: Skip
 
 
 [ $component == leg ]
 AdjacentStringLiteralsTest: Crash # Cannot call 'get:dartString' on "${s}".
@@ skipping 76 matching lines @@
 SuperAllNamedConstructorTest: Fail # Internal Error: Cannot find value
 SuperFieldAccessTest: Fail # Internal Error: SsaBuilder.visitIdentifier on non-this
 SuperFieldTest: Fail # no method named city in class B
 SuperOperatorTest: Fail # no method named + in class A
 SuperSetterTest: Fail # Internal Error: SsaBuilder.visitIdentifier on non-this
 SuperTest: Fail # cannot find tokens to produce error message for i++.
 SwitchFallthruTest: Fail # switch cases are not implemented
 SwitchLabelTest: Fail # switch cases are not implemented
 SwitchTest: Fail # switch cases are not implemented
 TopLevelPrefixedDeclarationTest: Fail # library prefixes not handled
-ToplevelCollision2Test/none: Fail # duplicate definition
 TypeDartcTest: Fail # non-empty instruction stack
 WhileTest: Fail # SsaBuilder for loop with aborting body not implemented
 WrongNumberTypeArgumentsTest*: Skip # multiple error annotations are required
 
 
 # Implementation errors (library or generated code).
 AssertionTest: Fail # Expect.equals(expected: <0>, actual: <null>) fails.
 BadNamedParametersTest: Fail # NullPointerException
 BitOperationsTest: Fail # Expect.equals(expected: <18446744073709552000>, actual: <1>) fails.
 ConstEscapeFrogTest: Fail # Expect.equals(expected: <null>, actual: <Instance of 'Bar'>) fails.
@@ skipping 176 matching lines @@
 ClosureBreakTest: Fail
 ExecuteFinally3Test: Fail
 ExecuteFinally9Test: Fail
 
 
 [ $component == leg && $mode == release ]
 AssignTopMethodNegativeTest: Crash
 
 [ $component == legium ]
 *: Skip