When `this` is context allocated inside a class constructor (strict mode
function), due to an arrow function, debug evaluate was unable to locate
the value. This is quick fix for the issue, which probably deserves a
more general rewrite at some later point in time (with more domain
expertise).

Bug: chromium:760225
Change-Id: I5208d8a202ad69439f60ada480599d0efcdc4ce4
Cq-Include-Trybots: luci.chromium.try:linux-rel,win7-rel
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1687412
Commit-Queue: Yang Guo <yangguo@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Auto-Submit: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62532}