TC39 agreed to disallow "use strict" directives in function body when
non-simple parameter lists are used.

This is a continuation of caitp's CL https://codereview.chromium.org/1281163002/
with some refactorings removed for now.

Still TODO: there is a lot of duplication between the is_simple field of
FormalParametersBase and the NonSimpleParameter property ExpressionClassifier
keeps track of. It should be possible to remove the former with a minor
refactoring of arrow function parsing. This will be attempted in a follow-up CL.

BUG=
LOG=N

Review URL: https://codereview.chromium.org/1300103005

Cr-Commit-Position: refs/heads/master@{#30388}