IDL: Support [NewObject] and [SameObject] extended attributes

This patch only adds the names to the list of allowed extended attribute,
so that having them in the IDL doesn't cause compilation errors.

Using them has no effect on the generated code; we're allowing them so
that IDL files can use the same syntax as specifications.

BUG=462913

Review URL: https://codereview.chromium.org/993543003

git-svn-id: svn://svn.chromium.org/blink/trunk@191621 bbb929c8-8fbe-4397-9dbb-9b2b20218538
3 files changed