The PrettyPrinter may have been valuable once, but with all the desugaring
now done in the parser the output is far from readable, and for some nodes
it's next-to-impossible to recreate the source from the AST. --print-ast is a
much more sensible place to look for human-readable info on what the parser did.

Review-Url: https://codereview.chromium.org/1974623002
Cr-Commit-Position: refs/heads/master@{#37730}