Second attempt to reland 69fafb5f
now that the maybe_assigned bug is fixed.

> Original change's description:
> Enable lazy source positions by default
>
> Also adds a compile time flag which allows the default to be configured
> so node can disable it since it hangs the node cpu profiler tests.
>
> Bug: v8:8510
> Change-Id: Idf4785036dc6242769410091518a67ac9179b718
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1491491
> Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
> Commit-Queue: Dan Elphick <delphick@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#62089}

Bug: v8:8510
Change-Id: Ia6d5d1d3a3c2b6a14c70ee67b02bec62a6a1a1d4
Cq-Include-Trybots: luci.v8.try:v8_linux_gc_stress_dbg, v8_linux64_gc_stress_custom_snapshot_dbg_ng
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1679498
Commit-Queue: Dan Elphick <delphick@chromium.org>
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62411}