--- a/testing/web-platform/tests/tools/wptrunner/wptrunner/wpttest.py
+++ b/testing/web-platform/tests/tools/wptrunner/wptrunner/wpttest.py
@@ -81,22 +81,16 @@ class RunInfo(dict):
             self["revision"] = rev
 
         self["product"] = product
         if debug is not None:
             self["debug"] = debug
         elif "debug" not in self:
             # Default to release
             self["debug"] = False
-        if product == "firefox" and "stylo" not in self:
-            self["stylo"] = False
-        if "STYLO_FORCE_ENABLED" in os.environ:
-            self["stylo"] = True
-        if "STYLO_FORCE_DISABLED" in os.environ:
-            self["stylo"] = False
         if browser_version:
             self["browser_version"] = browser_version
         if extras is not None:
             self.update(extras)
 
     def _update_mozinfo(self, metadata_root):
         """Add extra build information from a mozinfo.json file in a parent
         directory"""