Remove Expect from core library.

runtime/vm/dart_api_impl_test.cc

Index: runtime/vm/dart_api_impl_test.cc
diff --git a/runtime/vm/dart_api_impl_test.cc b/runtime/vm/dart_api_impl_test.cc
index 77860dba5b3893f11767ebca4eeac9df80e5fedb..c86756b71d63ebcc12a84e6659f51c3839e49cdb 100644
--- a/runtime/vm/dart_api_impl_test.cc
+++ b/runtime/vm/dart_api_impl_test.cc
@@ -6539,6 +6539,11 @@ TEST_CASE(NativeFunctionClosure) {
       "  int bar43(int i, int j, int k) {\n"
       "    var func = foo4; return func(i, j, k); }\n"
       "}\n"
+      "class Expect {\n"
+      "  static void equals(x, y) {\n"
+      "    if (x != y) throw new Error('not equal');\n"
+      "  }\n"
+      "}\n"
       "int testMain() {\n"
       "  Test obj = new Test();\n"
       "  Expect.equals(1, obj.foo1());\n"
@@ -6677,6 +6682,11 @@ TEST_CASE(NativeStaticFunctionClosure) {
       "  int bar43(int i, int j, int k) {\n"
       "    var func = foo4; return func(i, j, k); }\n"
       "}\n"
+      "class Expect {\n"
+      "  static void equals(x, y) {\n"
+      "    if (x != y) throw new Error('not equal');\n"
+      "  }\n"
+      "}\n"
       "int testMain() {\n"
       "  Test obj = new Test();\n"
       "  Expect.equals(0, Test.foo1());\n"