Start checking inputs to dart api functions.

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/object.h"
 
 namespace dart {
 
 class ApiState;
 class LocalHandle;
-class Object;
 class PersistentHandle;
-class RawObject;
-
 
 #define DARTSCOPE(isolate)                                                    \
   ASSERT(isolate != NULL);                                                    \
   Zone zone(isolate);                                                         \
   HANDLESCOPE(isolate);                                                       \
 
 class Api : AllStatic {
  public:
   // Creates a new local handle.
   static Dart_Handle NewLocalHandle(const Object& object);
 
   // Unwraps the raw object from the handle.
   static RawObject* UnwrapHandle(Dart_Handle object);
 
+  // Unwraps a raw Type from the handle.  The handle will be null if
+  // the object was not of the requested Type.
+#define DECLARE_UNWRAP(Type)                                                  \
+  static const Type& Unwrap##Type##Handle(Dart_Handle object);
+  CLASS_LIST_NO_OBJECT(DECLARE_UNWRAP)
+#undef DECLARE_UNWRAP
+
   // Validates and converts the passed in handle as a local handle.
   static LocalHandle* UnwrapAsLocalHandle(const ApiState& state,
                                           Dart_Handle object);
 
   // Validates and converts the passed in handle as a persistent handle.
   static PersistentHandle* UnwrapAsPersistentHandle(const ApiState& state,
                                                     Dart_Handle object);
 
   // Gets the handle used to designate successful return.
   static Dart_Handle Success();
@@ skipping 16 matching lines @@
   // Allocates space in the local zone.
   static uword Allocate(intptr_t size);
 
   // Reallocates space in the local zone.
   static uword Reallocate(uword ptr, intptr_t old_size, intptr_t new_size);
 };
 
 }  // namespace dart.
 
 #endif  // VM_DART_API_IMPL_H_