Make Dart_LoadLibrary and Dart_LoadSource take line and column offsets like Dart_LoadScript.

runtime/bin/gen_snapshot.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.
 
 // Generate a snapshot file after loading all the scripts specified on the
 // command line.
 
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
@@ skipping 310 matching lines @@
     if (tag == Dart_kImportTag) {
       return Builtin::LoadAndCheckLibrary(builtinId);
     }
     ASSERT(tag == Dart_kSourceTag);
     return DartUtils::NewError("Unable to part '%s' ", url_string);
   }
 
   if (libraryBuiltinId != Builtin::kInvalidLibrary) {
     // Special case for parting sources of a builtin library.
     if (tag == Dart_kSourceTag) {
-      return Dart_LoadSource(
-          library, url, Builtin::PartSource(libraryBuiltinId, url_string));
+      return Dart_LoadSource(library, url,
+          Builtin::PartSource(libraryBuiltinId, url_string), 0, 0);
     }
     ASSERT(tag == Dart_kImportTag);
     return DartUtils::NewError("Unable to import '%s' ", url_string);
   }
 
   Dart_Handle resolved_url = url;
   if (mapped_url_string != NULL) {
     // Mapped urls are relative to working directory.
     resolved_url = ResolveScriptUri(mapped_url_string);
     if (Dart_IsError(resolved_url)) {
@@ skipping 238 matching lines @@
   }
   return 0;
 }
 
 }  // namespace bin
 }  // namespace dart
 
 int main(int argc, char** argv) {
   return dart::bin::main(argc, argv);
 }