Reland "[blink] Remove work stealing"

This is a reland of 42aaff47209c95a505823b0834bdfe1d337ee1ff.

This was reverted because it was blocking another revert. That revert
relanded and has stuck, so this can reland now too.

Original change's description:
> [blink] Remove work stealing
>
> Work stealing is deprecated by script streaming on the task scheduler,
> and broken anyway by ScriptResource-controlled script streaming.
>
> Bug: 557466
> Bug: 761977
> Bug: 865098
> Bug: 866868
> Change-Id: Ie01d239b052ad7499e9884687bf95376a5cf6f9a
> Reviewed-on: https://chromium-review.googlesource.com/c/1258168
> Commit-Queue: Leszek Swirski <leszeks@chromium.org>
> Reviewed-by: Kouhei Ueno <kouhei@chromium.org>
> Reviewed-by: Daniel Vogelheim <vogelheim@chromium.org>
> Reviewed-by: Hiroshige Hayashizaki <hiroshige@chromium.org>
> Reviewed-by: Jochen Eisinger <jochen@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#601921}

TBR=hiroshige@chromium.org,kouhei@chromium.org,vogelheim@chromium.org,leszeks@chromium.org,jochen@chromium.org

Bug: 557466, 761977, 865098, 866868
Change-Id: Ibf7ac460f97bf7ab3699371c70076cb1e1d41d65
Reviewed-on: https://chromium-review.googlesource.com/c/1411601
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#622896}
18 files changed