View cart is really just a link to a page. It doesn't need anything fancy.
Change it to type="button" and that might do the trick.
If you still have issues change the onclick to: onClick="document.location.href='plugins'view-basket.php';"
The MM_goToURL behavior might be removed in recent versions of Dreamweaver. You can also just place an image with an <a href> to link to the cart page if you want to create your own view cart button.