Remove support for interfaces.

runtime/include/dart_api.h

 // 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.
 
 #ifndef INCLUDE_DART_API_H_
 #define INCLUDE_DART_API_H_
 
 /** \mainpage Dart Embedding API Reference
  *
  * Dart is a class-based programming language for creating structured
@@ skipping 1988 matching lines @@
  *   execution, then an error handle is returned.
  */
 DART_EXPORT Dart_Handle Dart_InvokeClosure(Dart_Handle closure,
                                            int number_of_arguments,
                                            Dart_Handle* arguments);
 
 // --- Classes and Interfaces ---
 
 /**
  * Is this a class handle?
- *
- * Most parts of the dart embedding api do not distinguish between
- * classes and interfaces.  For example, Dart_GetClass can return a
- * class or an interface and Dart_New can instantiate a class or an
- * interface.  The exceptions are Dart_IsClass and Dart_IsInterface,
- * which can be used to distinguish whether a handle refers to a class
- * or an interface.
  */
 DART_EXPORT bool Dart_IsClass(Dart_Handle handle);
 
 /**
- * Is this an interface handle?
- *
- * Most parts of the dart embedding api do not distinguish between
- * classes and interfaces.  For example, Dart_GetClass can return a
- * class or an interface and Dart_New can instantiate a class or an
- * interface.  The exceptions are Dart_IsClass and Dart_IsInterface,
- * which can be used to distinguish whether a handle refers to a class
- * or an interface.
+ * Is this an abstract class handle?
  */
-DART_EXPORT bool Dart_IsInterface(Dart_Handle handle);
+DART_EXPORT bool Dart_IsAbstractClass(Dart_Handle handle);
 
 /**
  * Returns the class name for the provided class or interface.
  */
 DART_EXPORT Dart_Handle Dart_ClassName(Dart_Handle clazz);
 
 /**
  * Returns the library for the provided class or interface.
  */
 DART_EXPORT Dart_Handle Dart_ClassGetLibrary(Dart_Handle clazz);
@@ skipping 741 matching lines @@
  *
  * \param object An object.
  * \param peer A value to store in the peer field.
  *
  * \return Returns an error if 'object' is a subtype of Null, num, or
  *   bool.
  */
 DART_EXPORT Dart_Handle Dart_SetPeer(Dart_Handle object, void* peer);
 
 #endif  // INCLUDE_DART_API_H_