Add test variant for experimental regexp engine

R=jgruber@chromium.org

Tbr: tmrts@chromium.org
Bug: v8:10765
Change-Id: I4c36614ef897c811cd4331802ad8ea5c90c5fd47
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2345228
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69443}

infra/testing/builders.pyl

@@ -336,6 +336,8 @@
       {'name': 'webkit', 'variant': 'stress_sampling'},
       # Stress snapshot.
       {'name': 'mjsunit', 'variant': 'stress_snapshot'},
+      # Experimental regexp engine.
+      {'name': 'mjsunit', 'variant': 'experimental_regexp'},
     ],
   },
   'v8_linux64_msan_rel_ng_triggered': {
@@ -997,6 +999,8 @@
       {'name': 'webkit', 'variant': 'stress_sampling'},
       # Stress snapshot.
       {'name': 'mjsunit', 'variant': 'stress_snapshot'},
+      # Experimental regexp engine.
+      {'name': 'mjsunit', 'variant': 'experimental_regexp'},
     ],
   },
   'V8 Linux64 - debug - perfetto': {
@@ -1027,6 +1031,8 @@
       {'name': 'webkit', 'variant': 'stress_sampling'},
       # Stress snapshot.
       {'name': 'mjsunit', 'variant': 'stress_snapshot'},
+      # Experimental regexp engine.
+      {'name': 'mjsunit', 'variant': 'experimental_regexp'},
     ],
   },
   'V8 Linux64 - gcov coverage': {

tools/testrunner/local/variants.py

@@ -12,6 +12,7 @@ ALL_VARIANT_FLAGS = {
   # Alias of exhaustive variants, but triggering new test framework features.
   "infra_staging": [[]],
   "interpreted_regexp": [["--regexp-interpret-all"]],
+  "experimental_regexp":  [["--enable-experimental-regexp-engine"]],
   "jitless": [["--jitless"]],
   "minor_mc": [["--minor-mc"]],
   "nci": [["--turbo-nci"]],