Remove support for legacy abstract declarations

runtime/vm/dart_api_impl_test.cc

 // 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.
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/json.h"
 #include "platform/utils.h"
 #include "vm/class_finalizer.h"
 #include "vm/dart_api_impl.h"
@@ skipping 4279 matching lines @@
       "  get c => 'bar';\n"
       "  set d(x) {}\n"
       "  get _e => 'bar';\n"
       "  set _f(x) {}\n"
       "  static g() => 'g';\n"
       "  static _h() => '_h';\n"
       "  static get i => 'i';\n"
       "  static set j(x) {}\n"
       "  static get _k => 'k';\n"
       "  static set _l(x) {}\n"
-      "  abstract m();\n"
-      "  abstract _n();\n"
-      "  abstract get o;\n"
-      "  abstract set p(x);\n"
-      "  abstract get _q;\n"
-      "  abstract set _r(x);\n"
+      "  m();\n"
+      "  _n();\n"
+      "  get o;\n"
+      "  set p(x);\n"
+      "  get _q;\n"
+      "  set _r(x);\n"
       "  s(x, [y, z]) {}\n"
       "  t([x, y, z]) {}\n"
       "  operator ==(x) {}\n"
       "}\n"
       "class _PrivateClass {\n"
       "  _PrivateClass() {}\n"
       "  _PrivateClass.named() {}\n"
       "}\n";
 
   Dart_Handle lib = TestCase::LoadTestScript(kScriptChars, NULL);
@@ skipping 3131 matching lines @@
   Dart_LoadSource(TestCase::lib(), url, source);
 
   dart_args[0] = Dart_NewInteger(1);
   result = Dart_Invoke(lib1, NewString("start"), 1, dart_args);
   EXPECT_VALID(result);
 }
 
 #endif  // defined(TARGET_ARCH_IA32) || defined(TARGET_ARCH_X64).
 
 }  // namespace dart