Update or delete language tests using obsolete interfaces or default factory

tests/language/syntax_test.dart

 // 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.
 
 class SyntaxTest {
   // "this" cannot be used as a field name.
   SyntaxTest this; /// 01: compile-time error
 
   // Syntax error.
   foo {} /// 02: compile-time error
@@ skipping 82 matching lines @@
 {}
 
 class Console
 native "=(typeof console == 'undefined' ? {} : console)" /// 29: compile-time error
 {}
 
 class NativeClass
 native "FooBar" /// 30: compile-time error
 {}
 
-interface Fisk {}
+abstract class Fisk {}
 
 class BoolImplementation implements Fisk
 native "Boolean" /// 31: compile-time error
 {}
 
 class _JSON
 native 'JSON' /// 32: compile-time error
 {}
 
 class ListFactory<E> implements List<E>
 native "Array" /// 33: compile-time error
 {}
 
-interface I extends UNKNOWN; /// 34: compile-time error
+abstract class I implements UNKNOWN; /// 34: compile-time error
 
 class XWindow extends DOMWindow
 hest "*Window" /// 35: compile-time error
 {}
 
 class XConsole
 hest "=(typeof console == 'undefined' ? {} : console)" /// 36: compile-time error
 {}
 
 class XNativeClass
@@ skipping 35 matching lines @@
 class YListFactory<E> implements List<E>
 for "Array" /// 46: compile-time error
 {}
 
 class A {
   const A()
   {} /// 47: compile-time error
   ;
 }
 
-interface G<T> {}
+abstract class G<T> {}
 
 typedef <T>(); /// 48: compile-time error
 
 class B
 extends void /// 49: compile-time error
 {}
 
 main() {
   try {
     new SyntaxTest();
@@ skipping 51 matching lines @@
 
   } catch (ex) {
     // Swallowing exceptions. Any error should be a compile-time error
     // which kills the current isolate.
   }
 }
 
 class Bad {
   factory Bad<Bad(String type) { return null; } /// 63: compile-time error
 }