Revert "[WPT] Test script's base URL used in dynamic imports"

This reverts commit 7e3a7255699cf3f8ac9bd3e31dadc69db293e06b.

Reason for revert: Consistent failures of
external/wpt/html/semantics/scripting-1/the-script-element/module/dynamic-import/alpha/base-url-worker.sub.html
in blink_web_tests on multiple builders started after this change landed.

Original change's description:
> [WPT] Test script's base URL used in dynamic imports
>
> This CL checks base URL used in resolving relative URL-like
> specifiers in dynamic imports() from
>
> - `<script>`s,
> - worker top-level scripts, and
> - worker scripts imported by `importScripts()`.
>
> This is for whatwg/html#5751.
>
> Bug: 1082086
> Change-Id: I778fb4d34b2e61f57799600006963c93aee5272c
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2198835
> Commit-Queue: Hiroshige Hayashizaki <hiroshige@chromium.org>
> Reviewed-by: Domenic Denicola <domenic@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#794492}

TBR=hiroshige@chromium.org,domenic@chromium.org

Change-Id: I2fd1c341c96d0364a6dbe6cce31a8c2630403b27
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 1082086
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2335460
Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#794657}