Performance issue with br tag

[sbondaryev]

Steps to reproduce

1. Go to: https://probablyup.com/markdown-to-jsx/
2. Replace content with (30 <b> tags):

<b>1</b><b>2</b><b>3</b><b>4</b><b>5</b><b>6</b><b>7</b><b>8</b><b>9</b><b>10</b>
<b>1</b><b>2</b><b>3</b><b>4</b><b>5</b><b>6</b><b>7</b><b>8</b><b>9</b><b>20</b>
<b>1</b><b>2</b><b>3</b><b>4</b><b>5</b><b>6</b><b>7</b><b>8</b><b>9</b><b>30</b>

3. Add <br /> on top of this content

Browser freezes

[camistein]

I'm experiencing the same issue, could it be related to: #136?

[quantizor]

Sorta... the regex for this HTML stuff is pretty intense