This is a reland of 3ca32e98

Original change's description:
> [regexp] Introduce species constructor protector for regexps.
> 
> Bug: v8:8445
> Change-Id: Iea69c65d0054b24b3f8c7234c4c556ebee2dd45f
> Reviewed-on: https://chromium-review.googlesource.com/c/1335696
> Reviewed-by: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#57564}

Bug: v8:8445
Change-Id: Ib79d716ff857eed95eed800b33ccb53f33d5167f
Reviewed-on: https://chromium-review.googlesource.com/c/1340286Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57598}

Add tests.

Bug: v8:5367
Cq-Include-Trybots: luci.chromium.try:linux_chromium_headless_rel;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I2a4215a87ba1dae98c4b25547494165f534b4a66
Reviewed-on: https://chromium-review.googlesource.com/1218046
Commit-Queue: Sathya Gunasekaran <gsathya@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Reviewed-by: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55974}

Bug: v8:7387
Change-Id: I831bf8f580d4112d7e0f48d90bbe2f44eff73225
Reviewed-on: https://chromium-review.googlesource.com/897326Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51047}

BUG=chromium:797581

Change-Id: I08f880a907f122480a014763975ecc07e2c49f7d
Reviewed-on: https://chromium-review.googlesource.com/856937Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50471}

The checked node and used node were mismatched. It checked if
"var_unique" is a string, but it used "key" which may not be a string.

Bug: v8:4911, v8:7161, chromium:800077
Change-Id: Ia2aee8b77ac33500430365a4800bf9cca40a28fc
Reviewed-on: https://chromium-review.googlesource.com/855138Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50435}