The assignment in default parameters (e.g., function foo(a = somedefault) { }
doesn't flow through PreParserFactory::NewAssignment even if the comment claims so.
Thus, piping through the variables is not needed.

Kudos to neis@ for pointing this out.

BUG=v8:5501
R=neis@chromium.org

Review-Url: https://codereview.chromium.org/2569983003
Cr-Commit-Position: refs/heads/master@{#41670}