chore: import upstream snapshot with attribution

lib/export/html-parser/stringify.ts

@@ -0,0 +1,30 @@
+import type { AST, ElementAST, ElementAttribute } from './types';
+import { voidTags } from './tags';
+
+export const formatAttributes = (attributes: ElementAttribute[]) => {
+  return attributes.reduce((attrs, attribute) => {
+    const { key, value } = attribute;
+    if (value === null) return `${attrs} ${key}`;
+    // Omit an empty style attribute, but keep the attributes accumulated so far.
+    // Returning '' here dropped every earlier attribute (this is a reduce).
+    if (key === 'style' && !value) return attrs;
+
+    const quoteEscape = value.indexOf("'") !== -1;
+    const quote = quoteEscape ? '"' : "'";
+    return `${attrs} ${key}=${quote}${value}${quote}`;
+  }, '');
+};
+
+export const toHTML = (tree: AST[]) => {
+  const htmlStrings: string[] = tree.map((node) => {
+    if (node.type === 'text') return node.content;
+    if (node.type === 'comment') return `<!--${node.content}-->`;
+
+    const { tagName, attributes, children } = node as ElementAST;
+    const isSelfClosing = voidTags.includes(tagName.toLowerCase());
+
+    if (isSelfClosing) return `<${tagName}${formatAttributes(attributes)}>`;
+    return `<${tagName}${formatAttributes(attributes)}>${toHTML(children)}</${tagName}>`;
+  });
+  return htmlStrings.join('');
+};