VM: Support bootstrapping core libraries from Kernel binaries instead of source.

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"
@@ skipping 92 matching lines @@
                                      strlen(source));
       }
       return src;
     }
   }
   return Dart_Null();  // Uri does not exist in path mapping information.
 }
 
 
 void Builtin::SetNativeResolver(BuiltinLibraryId id) {
-  UNREACHABLE();
+  ASSERT(static_cast<int>(id) >= 0);
+  ASSERT(static_cast<int>(id) < num_libs_);
+
+  if (builtin_libraries_[id].has_natives_) {
+    Dart_Handle url = DartUtils::NewString(builtin_libraries_[id].url_);
+    Dart_Handle library = Dart_LookupLibrary(url);
+    ASSERT(!Dart_IsError(library));
+    // Setup the native resolver for built in library functions.
+    DART_CHECK_VALID(
+        Dart_SetNativeResolver(library, NativeLookup, NativeSymbol));
+  }
 }
 
 
 Dart_Handle Builtin::LoadLibrary(Dart_Handle url, BuiltinLibraryId id) {
   ASSERT(static_cast<int>(id) >= 0);
   ASSERT(static_cast<int>(id) < num_libs_);
 
   Dart_Handle library = Dart_LoadLibrary(url, Dart_Null(), Source(id), 0, 0);
   if (!Dart_IsError(library) && (builtin_libraries_[id].has_natives_)) {
     // Setup the native resolver for built in library functions.
@@ skipping 30 matching lines @@
   Dart_Handle url = DartUtils::NewString(builtin_libraries_[id].url_);
   Dart_Handle library = Dart_LookupLibrary(url);
   if (Dart_IsError(library)) {
     library = LoadLibrary(url, id);
   }
   return library;
 }
 
 }  // namespace bin
 }  // namespace dart