Revert "Remove Expect from core library."

runtime/vm/snapshot_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_debugger_api.h"
 #include "platform/assert.h"
 #include "vm/bigint_operations.h"
 #include "vm/class_finalizer.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_api_message.h"
@@ skipping 893 matching lines @@
   const char* kScriptChars =
       "class Fields  {\n"
       "  Fields(int i, int j) : fld1 = i, fld2 = j {}\n"
       "  int fld1;\n"
       "  final int fld2;\n"
       "  final int bigint_fld = 0xfffffffffff;\n"
       "  static int fld3;\n"
       "  static const int smi_sfld = 10;\n"
       "  static const int bigint_sfld = 0xfffffffffff;\n"
       "}\n"
-      "class Expect {\n"
-      "  static void equals(x, y) {\n"
-      "    if (x != y) throw new RuntimeError('not equal');\n"
-      "  }\n"
-      "}\n"
       "class FieldsTest {\n"
       "  static Fields testMain() {\n"
       "    Expect.equals(true, Fields.bigint_sfld == 0xfffffffffff);\n"
       "    Fields obj = new Fields(10, 20);\n"
       "    Expect.equals(true, obj.bigint_fld == 0xfffffffffff);\n"
       "    return obj;\n"
       "  }\n"
       "}\n";
   Dart_Handle result;
 
@@ skipping 1275 matching lines @@
   EXPECT(Dart_ErrorHasException(result));
   EXPECT_SUBSTRING("Exception: nulltruefalse123456æøå3.14[]100123456789\n",
                    Dart_GetError(result));
 
   Dart_ExitScope();
 }
 
 #endif  // defined(TARGET_ARCH_IA32) || defined(TARGET_ARCH_X64).
 
 }  // namespace dart