TreeWizardVisit Method

Visit every ttype node in t, invoking the visitor. This is a quicker version of the general visit(t, pattern) method. The labels arg of the visitor action method is never set (it's null) since using a token type rather than a pattern doesn't let us set a label.

For all subtrees that match the pattern, execute the visit action. The implementation uses the root node of the pattern in combination with visit(t, ttype, visitor) so nil-rooted patterns are not allowed. Patterns with wildcard roots are also not allowed.