Convert implementation in mirrors.cc to use Dart_GetType instead of Dart_GetClass.

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 "include/dart_api.h"
 #include "include/dart_mirrors_api.h"
 #include "include/dart_native_api.h"
 #include "platform/assert.h"
 #include "platform/json.h"
@@ skipping 2797 matching lines @@
   EXPECT_VALID(Dart_ClassGetInterfaceCount(intf0, &len));
   EXPECT_EQ(0, len);
 
   len = -1;
   EXPECT_VALID(Dart_ClassGetInterfaceCount(intf1, &len));
   EXPECT_EQ(1, len);
   CHECK_CLASS(Dart_ClassGetInterfaceAt(intf1, 0), "MyInterface0");
 
   // Error cases.
   EXPECT_ERROR(Dart_ClassGetInterfaceCount(Dart_True(), &len),
-               "Dart_ClassGetInterfaceCount expects argument 'clazz' to be of "
-               "type Class.");
+               "Dart_ClassGetInterfaceCount expects argument 'object' to be of "
+               "type Class/Type.");
   EXPECT_ERROR(Dart_ClassGetInterfaceCount(Dart_NewApiError("MyError"), &len),
                "MyError");
 }
 
 
 TEST_CASE(TypeGetNonParamtericTypes) {
   const char* kScriptChars =
       "class MyClass0 {\n"
       "}\n"
       "\n"
@@ skipping 5312 matching lines @@
                                    NewString("main"),
                                    0,
                                    NULL);
   int64_t value = 0;
   result = Dart_IntegerToInt64(result, &value);
   EXPECT_VALID(result);
   EXPECT_EQ(8, value);
 }
 
 }  // namespace dart