Previously we had cached the source position information on
JSStackFrame (C++) objects and reused that between calls to
GetLineNumber() and GetColumnNumber(). The refactoring in
https://crrev.com/eed0d27c2f774b3adbc85d0a5fb30a8cf0f018a8
effectively removed that cache, while still making things
faster though.

This CL puts back the caching on the StackFrameInfo objects
by reusing the `offset` slot to store the computed source
position (as indicated by a bit in the `flags`). For promise
combinator async frames, the bit is always set and the
`offset_or_source_position` slot thus always contains the source
position (aka the `promise index` in this case). We also
added a `StackFrameInfo::ComputeLocation()` method to remove the
last remaining place where we'd peek into the StackFrameInfo from
outside stack-frame-info.{cc,h}.

Also-By: kimanh@chromium.org
Bug: chromium:1077657, v8:8742, chromium:1069425
Change-Id: I59e26a91965617163776e6cc2610b88e6925452c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2695386
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Auto-Submit: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72752}