Fixing custom element type extensions in Dartium to have correct native type ID

This is in support of the recent change to write the native type ID to the Dart wrappers

Dart changes for https://codereview.chromium.org/27769002/

BUG=14190
R=vsm@google.com

Review URL: https://codereview.chromium.org//29033003

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@28899 260f80e4-7a28-3924-810f-c04153c831b5
4 files changed