Error quickly if the embedder tries to load after Dart_Precompile.

runtime/vm/dart_api_impl.h

 // Copyright (c) 2011, 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.
 
 #ifndef VM_DART_API_IMPL_H_
 #define VM_DART_API_IMPL_H_
 
 #include "vm/allocation.h"
 #include "vm/native_arguments.h"
 #include "vm/object.h"
@@ skipping 298 matching lines @@
 
 // End a no Dart API call backs Scope.
 #define END_NO_CALLBACK_SCOPE(isolate)                                         \
   isolate->DecrementNoCallbackScopeDepth()
 
 #define CHECK_CALLBACK_STATE(isolate)                                          \
   if (isolate->no_callback_scope_depth() != 0) {                               \
     return reinterpret_cast<Dart_Handle>(Api::AcquiredError(isolate));         \
   }                                                                            \
 
+#define CHECK_COMPILATION_ALLOWED(isolate)                                     \
+  if (!isolate->compilation_allowed()) {                                       \
+    return Api::NewError("%s: Cannot load after Dart_Precompile",              \
+                         CURRENT_FUNC);                                        \
+  }                                                                            \
+
 #define ASSERT_CALLBACK_STATE(isolate)                                         \
   ASSERT(isolate->no_callback_scope_depth() == 0)
 
 }  // namespace dart.
 
 #endif  // VM_DART_API_IMPL_H_