Expressions like `foo() = 42` are specified as syntax errors but due to
web compat must be kept as runtime errors.

Bug: v8:10976
Change-Id: If2b549a3a1c35248c46319fa0e898872d40789a8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2471979
Auto-Submit: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Marja Hölttä <marja@chromium.org>
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70538}