The `testBuiltInObject` function verifies the presence of the specified
properties for *all* object types (not just function objects). Update
the error messages to reflect this.

In ES6 the function length property was changed to become
configurable.

- Updated DateTimeFormat tests for new handling of hour12 options property.
- Added a few invalid language tags to test of IsStructurallyValidLanguageTag.
- Added user-defined language tag to test of CanonicalizeLanguageTag.
- Added test for the Intl property of the global object.

Added tests for requirements imposed on the built-in objects of the ECMAScript Internationalization API Specification by the introduction of chapter 15 of the ECMAScript Language Specification.
- Removed some old tests that were redundant with the new tests.
- Added testBuiltInObject.js as standard include for all console tests in test262.py – see related bug 574.