That reduces the overhead of ParseAssignmentExpression at the cost of a few
more branches in the possible arrow head paths.

This also fixes the case where an outer scope of an arrow function didn't call eval
but a parameter initializer does. Previously the outer scope was also marked as
calling eval, causing worse performance. (Unlikely to happen though.)

Change-Id: I5263ef342f14e97372f5037fa659f32ec2ad6d34
Reviewed-on: https://chromium-review.googlesource.com/c/1352275
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57881}