Tell parser to skip pollsensor events by default, for the sake of J2ME

FB129304.

@ctsims I'm not certain whether the other PR, into master, is necessary or not (are we merging 2.14 back into master?) but I'm fairly certain that a PR into 2.14 *is* necessary.
(It's not super clear from the code but "Default Namespace" isn't actually the XForms namespace it's whatever the document namespace is)