Fix to asiva's code review comments on TBR Cl.

runtime/vm/mirrors_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_mirrors_api.h"
 
 #include "platform/assert.h"
 #include "vm/class_finalizer.h"
 #include "vm/dart.h"
 #include "vm/dart_api_impl.h"
@@ skipping 305 matching lines @@
   DARTSCOPE(isolate);
   const Library& lib = Api::UnwrapLibraryHandle(isolate, library);
   if (lib.IsNull()) {
     RETURN_TYPE_ERROR(isolate, library, Library);
   }
   const String& name = String::Handle(isolate, lib.name());
   ASSERT(!name.IsNull());
   return Api::NewHandle(isolate, name.raw());
 }
 
-DART_EXPORT Dart_Handle Dart_LibraryId(Dart_Handle library,
-                                       intptr_t* library_id) {
-  Isolate* isolate = Isolate::Current();
-  DARTSCOPE(isolate);
-  const Library& lib = Api::UnwrapLibraryHandle(isolate, library);
-  if (lib.IsNull()) {
-    RETURN_TYPE_ERROR(isolate, library, Library);
-  }
-  if (library_id != NULL) {
-    *library_id = lib.index();
-  }
-  return Api::Success();
-}
-
 DART_EXPORT Dart_Handle Dart_LibraryGetClassNames(Dart_Handle library) {
   Isolate* isolate = Isolate::Current();
   DARTSCOPE(isolate);
   const Library& lib = Api::UnwrapLibraryHandle(isolate, library);
   if (lib.IsNull()) {
     RETURN_TYPE_ERROR(isolate, library, Library);
   }
 
   const GrowableObjectArray& names =
       GrowableObjectArray::Handle(isolate, GrowableObjectArray::New());
@@ skipping 29 matching lines @@
     RETURN_TYPE_ERROR(isolate, closure, Instance);
   }
 
   ASSERT(ClassFinalizer::AllClassesFinalized());
 
   RawFunction* rf = Closure::function(closure_obj);
   return Api::NewHandle(isolate, rf);
 }
 
 }  // namespace dart