Only pass around the unadulterated value identifier in the VisitResult class
until the very last moment before code generation, at which point the
declaration that was used to originally define the value is used to generate the
correct final source code string in the context of a l-value or r-value.

Bug: v8:7793
Change-Id: Ifd0c0d245b2eb65c7f3ddb1ad4c87ee235c54a82
Reviewed-on: https://chromium-review.googlesource.com/1125063
Commit-Queue: Daniel Clifford <danno@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54229}