Use patching for dart:io.

runtime/bin/builtin.cc

 // 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.
 
 #include <stdio.h>
 
 #include "include/dart_api.h"
 
 #include "bin/builtin.h"
 #include "bin/dartutils.h"
 
 
 Builtin::builtin_lib_props Builtin::builtin_libraries_[] = {
-  /*      url_                    source_       has_natives_  */
-  { DartUtils::kBuiltinLibURL, builtin_source_, true  },
-  { DartUtils::kJsonLibURL,    json_source_,    false },
-  { DartUtils::kUriLibURL,     uri_source_,     false },
-  { DartUtils::kCryptoLibURL,  crypto_source_,  false },
-  { DartUtils::kIOLibURL,      io_source_,      true  },
-  { DartUtils::kUtfLibURL,     utf_source_,     false }
+  /* { url_, source_, patch_url_, patch_source_, has_natives_ } */
+  { DartUtils::kBuiltinLibURL, builtin_source_, NULL, NULL, true },
+  { DartUtils::kJsonLibURL, json_source_, NULL, NULL, false },
+  { DartUtils::kUriLibURL, uri_source_, NULL, NULL, false },
+  { DartUtils::kCryptoLibURL, crypto_source_, NULL, NULL, false },
+  { DartUtils::kIOLibURL, io_source_,
+    DartUtils::kIOLibPatchURL, io_patch_, true },
+  { DartUtils::kUtfLibURL, utf_source_, NULL, NULL, false }
 };
 
 
 Dart_Handle Builtin::Source(BuiltinLibraryId id) {
   ASSERT((sizeof(builtin_libraries_) / sizeof(builtin_lib_props)) ==
          kInvalidLibrary);
   ASSERT(id >= kBuiltinLibrary && id < kInvalidLibrary);
   return Dart_NewString(builtin_libraries_[id].source_);
 }
 
 
 void Builtin::SetNativeResolver(BuiltinLibraryId id) {
   UNREACHABLE();
 }
 
 
 Dart_Handle Builtin::LoadAndCheckLibrary(BuiltinLibraryId id) {
   ASSERT((sizeof(builtin_libraries_) / sizeof(builtin_lib_props)) ==
          kInvalidLibrary);
   ASSERT(id >= kBuiltinLibrary && id < kInvalidLibrary);
   Dart_Handle url = Dart_NewString(builtin_libraries_[id].url_);
   Dart_Handle library = Dart_LookupLibrary(url);
   if (Dart_IsError(library)) {
     library = Dart_LoadLibrary(url, Source(id));
     if (!Dart_IsError(library) && (builtin_libraries_[id].has_natives_)) {
       // Setup the native resolver for built in library functions.
       DART_CHECK_VALID(Dart_SetNativeResolver(library, NativeLookup));
     }
+    if (builtin_libraries_[id].patch_url_ != NULL) {
+      ASSERT(builtin_libraries_[id].patch_source_ != NULL);
+      Dart_Handle patch_url = Dart_NewString(builtin_libraries_[id].patch_url_);
+      Dart_Handle patch_source =
+          Dart_NewString(builtin_libraries_[id].patch_source_);
+      DART_CHECK_VALID(Dart_LoadPatch(library, patch_url, patch_source));
+    }
   }
   DART_CHECK_VALID(library);
   return library;
 }