Revert of flag simplification.

In order to unify WebRTC recipes with Chromium recipes this CL tries to revert the old CL https://webrtc-review.googlesource.com/c/src/+/171681.
This CL was already partially reverted (https://webrtc-review.googlesource.com/c/src/+/171809).
In upcoming CLs, the added flag dump_json_test_results will be removed in order to use isolated-script-test-output instead.

Bug: webrtc:13556
Change-Id: I3144498b9a5cbaa56c23b3b8adbac2229ad63c37
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/245602
Reviewed-by: Andrey Logvin <landrey@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Commit-Queue: Jeremy Leconte <jleconte@google.com>
Cr-Commit-Position: refs/heads/main@{#35666}
diff --git a/tools_webrtc/flags_compatibility.py b/tools_webrtc/flags_compatibility.py
index c716574..caad537 100755
--- a/tools_webrtc/flags_compatibility.py
+++ b/tools_webrtc/flags_compatibility.py
@@ -15,32 +15,36 @@
 
 
 def main():
-    parser = argparse.ArgumentParser()
-    parser.add_argument('--isolated-script-test-perf-output')
-    args, unrecognized_args = parser.parse_known_args()
+  parser = argparse.ArgumentParser()
+  parser.add_argument('--isolated-script-test-output')
+  parser.add_argument('--isolated-script-test-perf-output')
+  args, unrecognized_args = parser.parse_known_args()
 
-    test_command = _ForcePythonInterpreter(unrecognized_args)
-    if args.isolated_script_test_perf_output:
-        test_command += [
-            '--isolated_script_test_perf_output=' +
-            args.isolated_script_test_perf_output
-        ]
-    logging.info('Running %r', test_command)
+  test_command = _ForcePythonInterpreter(unrecognized_args)
+  if args.isolated_script_test_output:
+    test_command += [
+        '--isolated_script_test_output', args.isolated_script_test_output
+    ]
+  if args.isolated_script_test_perf_output:
+    test_command += [
+        '--isolated_script_test_perf_output=' +
+        args.isolated_script_test_perf_output
+    ]
+  logging.info('Running %r', test_command)
 
-    return subprocess.call(test_command)
+  return subprocess.call(test_command)
 
 
 def _ForcePythonInterpreter(cmd):
-    """Returns the fixed command line to call the right python executable."""
-    out = cmd[:]
-    if out[0] == 'python':
-        out[0] = sys.executable
-    elif out[0].endswith('.py'):
-        out.insert(0, sys.executable)
-    return out
+  """Returns the fixed command line to call the right python executable."""
+  out = cmd[:]
+  if out[0] == 'python':
+    out[0] = sys.executable
+  elif out[0].endswith('.py'):
+    out.insert(0, sys.executable)
+  return out
 
 
 if __name__ == '__main__':
-    # pylint: disable=W0101
-    logging.basicConfig(level=logging.INFO)
-    sys.exit(main())
+  logging.basicConfig(level=logging.INFO)
+  sys.exit(main())