Deal with extension loading from packages.

runtime/bin/extensions.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 "bin/extensions.h"
 
 #include <stdio.h>
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/globals.h"
 #include "bin/dartutils.h"
 #include "bin/file.h"
 
 Dart_Handle Extensions::LoadExtension(const char* extension_url,
                                       Dart_Handle parent_library) {
   char* library_path = strdup(extension_url);
-  if (!library_path || !File::IsAbsolutePath(library_path)) {
-    free(library_path);
-    return Dart_Error("unexpected error in library path");
+
+  if (library_path == NULL) {
+    return Dart_Error("Out of memory in LoadExtension");
   }
+
   // Extract the path and the extension name from the url.
   char* last_path_separator = strrchr(library_path, '/');
   char* extension_name = last_path_separator + 1;
   *last_path_separator = '\0';  // Terminate library_path at last separator.
 
   void* library_handle = LoadExtensionLibrary(library_path, extension_name);
-  if (!library_handle) {
+  if (library_handle == NULL) {
     free(library_path);
     return Dart_Error("cannot find extension library");
   }
 
   const char* strings[] = { extension_name, "_Init", NULL };
   char* init_function_name = Concatenate(strings);
   typedef Dart_Handle (*InitFunctionType)(Dart_Handle import_map);
   InitFunctionType fn = reinterpret_cast<InitFunctionType>(
       ResolveSymbol(library_handle, init_function_name));
   free(init_function_name);
@@ skipping 15 matching lines @@
   }
   char* result = reinterpret_cast<char*>(malloc(size));
   int index = 0;
   for (int i = 0; strings[i] != NULL; i++) {
     index += snprintf(result + index, size - index, "%s", strings[i]);
   }
   ASSERT(index == size - 1);
   ASSERT(result[size - 1] == '\0');
   return result;
 }