This reverts commit a241576f.

Bytecode array visitor has a side-effect of incrementing the age counter.

This patch makes the increment atomic and thus safe for the concurrent
marker.

Bug: chromium:694255
Change-Id: Ibe1d75714a5911385b06e52ed50b5f152ec6b73d
Reviewed-on: https://chromium-review.googlesource.com/622432
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47472}