Remove legacy patch class syntax in VM

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 "bin/builtin.h"
 #include "vm/compiler.h"
 #include "include/dart_api.h"
 #include "include/dart_mirrors_api.h"
 #include "include/dart_native_api.h"
 #include "include/dart_tools_api.h"
@@ skipping 6649 matching lines @@
 }
 
 
 TEST_CASE(LoadPatch) {
   const char* kLibrary1Chars =
       "library library1_name;";
   const char* kSourceChars =
       "part of library1_name;\n"
       "external int foo();";
   const char* kPatchChars =
-      "patch int foo() => 42;";
+      "@patch int foo() => 42;";
 
   // Load up a library.
   Dart_Handle url = NewString("library1_url");
   Dart_Handle source = NewString(kLibrary1Chars);
   Dart_Handle lib = Dart_LoadLibrary(url, Dart_Null(), source, 0, 0);
   EXPECT_VALID(lib);
   EXPECT(Dart_IsLibrary(lib));
 
   url = NewString("source_url");
   source = NewString(kSourceChars);
@@ skipping 24 matching lines @@
   const char* kLibrary1Chars =
       "library library1_name;";
   const char* kSourceChars =
       "part of library1_name;\n"
       "external int foo([int x]);\n"
       "class Foo {\n"
       "  external static int addDefault10([int x, int y]);\n"
       "}";
   const char* kPatchChars =
       "const _UNDEFINED = const Object();\n"
-      "patch foo([x=_UNDEFINED]) => identical(x, _UNDEFINED) ? 42 : x;\n"
-      "patch class Foo {\n"
+      "@patch foo([x=_UNDEFINED]) => identical(x, _UNDEFINED) ? 42 : x;\n"
+      "@patch class Foo {\n"
       "  static addDefault10([x=_UNDEFINED, y=_UNDEFINED]) {\n"
       "    if (identical(x, _UNDEFINED)) x = 10;\n"
       "    if (identical(y, _UNDEFINED)) y = 10;\n"
       "    return x + y;\n"
       "  }\n"
       "}";
 
   bool old_flag_value = FLAG_ignore_patch_signature_mismatch;
   FLAG_ignore_patch_signature_mismatch = true;
 
@@ skipping 3487 matching lines @@
   result = Dart_Invoke(lib,
                        NewString("foozoo"),
                        0,
                        NULL);
   EXPECT(Dart_IsError(result));
 }
 
 #endif  // !PRODUCT
 
 }  // namespace dart