Don't enumerate Function.prototype.{connect,disconnect}

Don't enumerate Function.prototype.{connect,disconnect}

QML/JS adds connect and disconnect methods to the standard
Function.prototype object.
Follow the convention of ECMA-262: Function properties should
be non-enumerable.
In particular, we don't want such built-in properties to show
up in user code "for-in" statements.

Task-number: QTBUG-21120
Change-Id: I416106badf35daddf32e16f757d37b2b09e58310
Reviewed-on: http://codereview.qt.nokia.com/3587
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Jędrzej Nowacki <jedrzej.nowacki@nokia.com>