Attempt to set read-only props using attr.

Fixes https://github.com/sveltejs/svelte/issues/2732

src/internal/dom.js

@@ -93,7 +93,11 @@ export function set_attributes(node, attributes) {
 		if (key === 'style') {
 			node.style.cssText = attributes[key];
 		} else if (key in node) {
+			try {
 				node[key] = attributes[key];
+			} catch (e) {
+				attr(node, key, attributes[key]);
+			}
 		} else {
 			attr(node, key, attributes[key]);
 		}