Blockquote Tag "name" parsing problem

### Is this a hackmd.io issue?

- [x] Yes, the bug happens on https://hackmd.io
- [ ] No. If it's a self-hosted CodiMD instance, please fire up the issue in the repo of CodiMD: https://github.com/hackmdio/codimd

### What's the problem
Some time ago (a year or so), it was possible to use "name" blockquote tag to point a source of a quote as a clickable URL, e.g. `>[name=[foo](http://www.bar.org)]`, now it can't be properly parsed at all (please see screenshot below).

Now it is possible to use a URL in the "name" blockquote tag to point to a source, e.g. `>[name=`. It will not be properly parsed and will not work as a link, but at least it will change its own decorations. But if your blockquote has a few paragraphs, it also could not be properly parsed, but not in 100% cases (please see examples below).

#### Current behavior


Steps to reproduce link error:
1. Write blockquote
2. Try to use 'name' tag as a link, e.g. `>[name=[foo](http://www.bar.org)]`
3. See error

Steps to reproduce url error:
1. Write blockquote
2. Try to use 'name' tag as a link, e.g. `>[name=`
3. See error if your quote blog is long enough

Note with all examples: https://hackmd.io/@banderlog/rJJ24HRQu

#### Expected behaviour

Proper markdown parsing in all cases.

#### Environment

I use HackMD on:

**Desktop**
- OS: Ubuntu 18.04 LTS
- Browser: Firefox
- Browser Version: 86.0