This adds support for mshtml host object accessor to jscript, with necessary fixes along the way.
For the last patch I decided to go with flags (i.e. PROPF_METHOD) instead of introducing a type field, which makes it simpler, less fields to track off and less changes.
-- v2: jscript|mshtml: Add support for host object accessor props. mshtml: Move the hook invocations inside of the builtin_prop* helpers. mshtml: Fix builtin style translation in removeAttribute for IE9+ modes. mshtml: Move lookup_dispid and get_dispid calls out of get_builtin_id. mshtml: Don't make hidden props enumerable.