According to spec https://tc39.github.io/ecma262/#sec-object.assign,
https://tc39.github.io/ecma262/#sec-ordinaryownpropertykeys, object.assign should copy symbols last. The current implementation ignores that order.
The idea of the fix here is to do iteration twice, one to skip symbol first then one to skip string.

Bug: v8:6705
Change-Id: I27a353e0c44a8f7adcf55d7143dd3ce26bea2724
Reviewed-on: https://chromium-review.googlesource.com/c/1432597
Commit-Queue: Z Nguyen-Huu <duongn@microsoft.com>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59258}