This reverts commit 4d7ad46d.

Reason for revert: Makes i18n bot red
https://logs.chromium.org/v/?s=chromium%2Fbb%2Fclient.v8%2FV8_Linux_-_noi18n_-_debug%2F20162%2F%2B%2Frecipes%2Fsteps%2FCheck%2F0%2Flogs%2FAssemblerIa32JumpTabl..%2F0

Original change's description:
> Introduce CodeReference
> 
> Add a struct CodeReference that can be stack allocated to pass a
> reference to either an on-heap code object or off-heap WasmCode object
> in a gc safe manner. The struct also provides a common interface such
> that code can be written independently of the kind of code object it
> references.
> 
> Change-Id: I5a6f74462e6e141d167c7fd9bac8c21941fd83b1
> Reviewed-on: https://chromium-review.googlesource.com/977905
> Commit-Queue: Stephan Herhut <herhut@chromium.org>
> Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#52580}

TBR=mstarzinger@chromium.org,herhut@chromium.org

Change-Id: I9c49da9ee97e7423284e58bec3fdc1d212ff1af0
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/1010544Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52582}