Revert of [worklets] Introduce ThreadedWorkletMessagingProxy and AnimationWorkletMessagaingProxy. (patchset #8 id:180001 of https://codereview.chromium.org/2312493002/ )

Reason for revert:
Caused leaks in a number of layout tests.

https://build.chromium.org/p/chromium.webkit/builders/WebKit%20Linux%20Leak/builds/22941

Original issue's description:
> [worklets] Introduce ThreadedWorkletMessagingProxy and AnimationWorkletMessagaingProxy.
>
> This patch does the plumbing from the animationworklet to the globalscope to import scripts etc.
>
> BUG=567358
>
> Committed: https://crrev.com/4bd1a1b4e1d321526cfe0c10adc15f507a661bb8
> Cr-Commit-Position: refs/heads/master@{#418765}

TBR=nhiroki@chromium.org,hongchan@chromium.org,yhirano@chromium.org,majidvp@chromium.org,ikilpatrick@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=567358

Review-Url: https://codereview.chromium.org/2342013002
Cr-Commit-Position: refs/heads/master@{#418799}
14 files changed