[test] Expose variant flags in json output

For standard test failures, the variant name is enough to deduce the
full command line of the test. This is used to create the flako
command line on the infra side.

Test failures from numfuzz have additional variant_flags, calculated
by the fuzzer, which don't match a variant name. Exposing those in
the test results will enable printing a proper flako command line
on infra side for numfuzz cases.

Bug: v8:8971
Change-Id: Ie47d42a0b34037da458b474f2a9ab38f1a5d238a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1554689Reviewed-by: Sergiy Belozorov <sergiyb@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60656}

tools/testrunner/testproc/progress.py

@@ -307,6 +307,7 @@ class JsonTestProgressIndicator(ProgressIndicator):
         "random_seed": test.random_seed,
         "target_name": test.get_shell(),
         "variant": test.variant,
+        "variant_flags": test.variant_flags,
       })
 
   def finished(self):

tools/unittests/testdata/expected_test_results1.json

@@ -23,7 +23,8 @@
       "stderr": "",
       "stdout": "--test strawberries --random-seed=123 --nohard-abort\n",
       "target_name": "d8_mocked.py",
-      "variant": "default"
+      "variant": "default",
+      "variant_flags": []
     },
     {
       "command": "/usr/bin/python out/Release/d8_mocked.py --test strawberries --random-seed=123 --nohard-abort",
@@ -45,7 +46,8 @@
       "stderr": "",
       "stdout": "--test strawberries --random-seed=123 --nohard-abort\n",
       "target_name": "d8_mocked.py",
-      "variant": "default"
+      "variant": "default",
+      "variant_flags": []
     },
     {
       "command": "/usr/bin/python out/Release/d8_mocked.py --test strawberries --random-seed=123 --nohard-abort",
@@ -67,7 +69,8 @@
       "stderr": "",
       "stdout": "--test strawberries --random-seed=123 --nohard-abort\n",
       "target_name": "d8_mocked.py",
-      "variant": "default"
+      "variant": "default",
+      "variant_flags": []
     }
   ],
   "slowest_tests": [

tools/unittests/testdata/expected_test_results2.json

@@ -22,7 +22,8 @@
       "stderr": "",
       "stdout": "bananaflakes --random-seed=123 --nohard-abort\n",
       "target_name": "d8_mocked.py",
-      "variant": "default"
+      "variant": "default",
+      "variant_flags": []
     },
     {
       "command": "/usr/bin/python out/Release/d8_mocked.py bananaflakes --random-seed=123 --nohard-abort",
@@ -43,7 +44,8 @@
       "stderr": "",
       "stdout": "bananaflakes --random-seed=123 --nohard-abort\n",
       "target_name": "d8_mocked.py",
-      "variant": "default"
+      "variant": "default",
+      "variant_flags": []
     }
   ],
   "slowest_tests": [