Revert of Encode interpreter::SourcePositionTable as variable-length ints. (patchset #10 id:200001 of https://codereview.chromium.org/1704943002/ )

Reason for revert:
Build failure on Linux64 arm64 ASAN:

http://build.chromium.org/p/client.v8/builders/V8%20Linux64%20ASAN%20arm64%20-%20debug%20builder/builds/4829

(Leaks memory, somehow.)

Original issue's description:
> Encode interpreter::SourcePositionTable as variable-length ints.
>
> This reduces the memory consumption of SourcePositionTable by ca. 2/3.
> Over Octane, this reduces the source position table memory consumption
> from ~370kB to ~115kB, which makes it ca. 10% of the total bytecode size
> (~1.1MB)
>
> BUG=
>
> Committed: https://crrev.com/a6f41f7b8226555c5900440f6e3092b3545ee0f6
> Cr-Commit-Position: refs/heads/master@{#34250}

TBR=jochen@chromium.org,rmcilroy@chromium.org,yangguo@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=

Review URL: https://codereview.chromium.org/1728193003

Cr-Commit-Position: refs/heads/master@{#34251}