CustomWebElement class must implement WebElement Interface.

[sidnc86]

This would allow to easily cast from WebElement reference. Consider a scenario where a call to findElement() returns WebElement but we would like to have

ButtonElement b = (ButtonElement)wd.findElement(...);

This would simplify quite a lot of similar scenarios.

[sidnc86]

Another advantage this provides is in context of reusability of methods like getTagName() as described in Issue#2