add back experimental download

Author: T4rk1n

dash/testing/browser.py

@@ -485,6 +485,17 @@ def _get_chrome(self):
         if "DASH_TEST_CHROMEPATH" in os.environ:
             options.binary_location = os.environ["DASH_TEST_CHROMEPATH"]
 
+        options.add_experimental_option(
+            "prefs",
+            {
+                "download.default_directory": self.download_path,
+                "download.prompt_for_download": False,
+                "download.directory_upgrade": True,
+                "safebrowsing.enabled": False,
+                "safebrowsing.disable_download_protection": True,
+            },
+        )
+
         options.add_argument("--disable-dev-shm-usage")
         options.add_argument("--no-sandbox")
         options.add_argument("--disable-gpu")