fix(markup): keep list items on separate lines in quote replies (#40329)

Keep each list item on its own line when quoting a comment. Items
containing bold text or links could run together in the reply editor,
breaking the quoted list.

web_src/js/markup/html2markdown.test.ts

@@ -21,4 +21,5 @@ test('convertHtmlToMarkdown', () => {
 
   expect(convertHtmlToMarkdown(h(`<ol><li>a<ul><li>b</li></ul></li></ol>`))).toBe('1. a\n    * b\n\n');
   expect(convertHtmlToMarkdown(h(`<ol><li><input checked>a</li></ol>`))).toBe('1. [x] a\n');
+  expect(convertHtmlToMarkdown(h(`<ul><li><strong>a</strong></li><li><a href="link">b</a></li><li>c</li></ul>`))).toBe('* **a**\n* [b](link)\n* c\n');
 });

web_src/js/markup/html2markdown.ts

@@ -82,6 +82,7 @@ function processElement(ctx :ProcessorContext, processors: Processors, el: HTMLE
     return processElement(ctx, processors, el.firstElementChild as HTMLElement);
   }
 
+  const {elementIsFirst, elementIsLast} = ctx; // processing the children below overwrites them
   const isListContainer = el.tagName === 'OL' || el.tagName === 'UL';
   if (isListContainer) ctx.listNestingLevel++;
   for (let i = 0; i < el.children.length; i++) {
@@ -91,6 +92,8 @@ function processElement(ctx :ProcessorContext, processors: Processors, el: HTMLE
   }
   if (isListContainer) ctx.listNestingLevel--;
 
+  ctx.elementIsFirst = elementIsFirst;
+  ctx.elementIsLast = elementIsLast;
   if (processors[el.tagName]) {
     const ret = processors[el.tagName](el);
     if (ret && ret !== el) {