NFC: Inline handling of DependentSizedArrayType

Summary:
Re-order handling of getElementType and getBracketsRange. It is
necessary to perform all printing before any traversal to child nodes.

This causes no change in the output of ast-dump-array.cpp due to the way
child nodes are printed with a delay.  This new order of the code is
also the order that produces the expected output anyway.

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D55257

llvm-svn: 348409