prevent removing SVG sprites when saving selected content

lib/single-file/single-file-core.js

@@ -976,7 +976,8 @@ this.SingleFileCore = this.SingleFileCore || (() => {
 				let elementFound = false;
 				Array.from(parentElement.childNodes).forEach(node => {
 					elementFound = elementFound || (node == element);
-					if (node != element && node.tagName != "STYLE" && node.tagName != "LINK") {
+					const tagName = node.tagName && node.tagName.toLowerCase();
+					if (node != element && tagName != "svg" && tagName != "style" && tagName != "link") {
 						if (elementFound) {
 							node.remove();
 						} else {