Add a toJson method to Browser so it becomes easier to use in Capabilities

Author: shs96c

java/src/org/openqa/selenium/remote/Browser.java

@@ -72,4 +72,8 @@ public boolean is(String browserName) {
       return browserName().equals(browserName) || "Safari".equals(browserName);
     }
   };
+
+  default String toJson() {
+    return browserName();
+  }
 }