Reading the proper pc, fp and sp in a JSEntry frame is in a different
offset than in the regular frames.

Bug: v8:10779, v8:10833
Fixes: v8:10779
Change-Id: I9aec44276fba0aab95b761ab17a16ec3767f4eb8
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2369173
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69582}