Do not remove escaping from brackets, fixes #2703

Removed the erroneous replacement of escaped brackets with
plain brackets as this breaks valid markdown.
Added a test case for this.

Signed-off-by: Ferdinand Thiessen <rpm@fthiessen.de>

Author: susnux

src/extensions/Markdown.js

@@ -79,8 +79,6 @@ const createMarkdownSerializer = ({ nodes, marks }) => {
 		),
 		serialize(content, options) {
 			return this.serializer.serialize(content, { ...options, tightLists: true })
-				.split('\\[').join('[')
-				.split('\\]').join(']')
 		},
 	}
 }

src/tests/markdown.spec.js

@@ -85,6 +85,8 @@ describe('Markdown though editor', () => {
 	test('links', () => {
 		expect(markdownThroughEditor('[test](foo)')).toBe('[test](foo)')
 		expect(markdownThroughEditor('[test](foo "bar")')).toBe('[test](foo "bar")')
+		// Issue #2703
+		expect(markdownThroughEditor('[bar\\\\]: /uri\n\n[bar\\\\]')).toBe('[bar\\\\](/uri)')
 	})
 	test('images', () => {
 		expect(markdownThroughEditor('![test](foo)')).toBe('![test](foo)')