Fix windows build compilation error.

runtime/vm/dart_api_impl.cc

 // Copyright (c) 2013, 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 "include/dart_mirrors_api.h"
 #include "include/dart_native_api.h"
 
 #include "platform/assert.h"
 #include "lib/stacktrace.h"
@@ skipping 1529 matching lines @@
     Dart_ExitIsolate();
     RunLoopData data;
     data.monitor = &monitor;
     data.done = false;
     I->message_handler()->Run(
         Dart::thread_pool(),
         NULL, RunLoopDone, reinterpret_cast<uword>(&data));
     while (!data.done) {
       ml.Wait();
     }
-    Dart_EnterIsolate(Api::CastIsolate(I));
+    ::Dart_EnterIsolate(Api::CastIsolate(I));
   }
   if (I->object_store()->sticky_error() != Object::null()) {
     Dart_Handle error = Api::NewHandle(T, I->object_store()->sticky_error());
     I->object_store()->clear_sticky_error();
     return error;
   }
   if (FLAG_print_class_table) {
     HANDLESCOPE(T);
     I->class_table()->Print();
   }
@@ skipping 4451 matching lines @@
   return Api::Success();
 }
 #endif  // DART_PRECOMPILED_RUNTIME
 
 
 DART_EXPORT bool Dart_IsRunningPrecompiledCode() {
   return Dart::IsRunningPrecompiledCode();
 }
 
 }  // namespace dart