Remove need for shuffling of accumulator and operand registers when
suspending a generator

BUG=v8:6351
TBR=bmeurer@chromium.org

Change-Id: I372509adc03b9781716412b809639554fe16e372
Reviewed-on: https://chromium-review.googlesource.com/578377
Commit-Queue: Caitlin Potter <caitp@igalia.com>
Reviewed-by: Caitlin Potter <caitp@igalia.com>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46883}