Instead of unconditionally parsing the catch parameter as an expression
and then recovering if it turns out to be a simple variable proxy
(the overwhelmingly common case), this patch peeks one token ahead
before attempting to parse. This avoids doing the usual RemoveUnresolved
gymnastics in ParseTryStatement, and as a side-effect slightly improves
function name inference for an async arrow function test case.

Review-Url: https://codereview.chromium.org/2151433005
Cr-Commit-Position: refs/heads/master@{#37780}