Run firefox in blank profile when e2e testing

e2e/marionette.scm

@@ -25,8 +25,11 @@
 		(when pid (close-firefox pid))))))
 
 (define (start-firefox)
-  (let* ((i/o (pipe))
-		 (pid (spawn "firefox" '("firefox" "--marionette" "--headless")
+  (let* ((profile-dir (mkdtemp "/tmp/marionette-XXXXXX"))
+		 (i/o (pipe))
+		 (pid (spawn "firefox"
+					 `("firefox" "--marionette" "--headless"
+					   "--profile" ,profile-dir "about:blank")
 					 #:output (cdr i/o)
 					 #:error (cdr i/o))))
 	(let loop ((line (read-line (car i/o))))