Paragraph tags removed from div elements if script tag is present

[dankop]

I honestly have no idea how to summarize this bug (therefore my lousy title), so I'll best skip right to how to reproduce it.

• Get 10 paragraphs of text from Lorem Ipsum, and paste it to your visual editor.
• Switch to the text editor and wrap the first 5 paragraphs in a div, and wrap the last 5 in a second div.
• After the first paragraph in each div, simply write <script></script>
• Switch between Visual and Text editor, and watch the paragraphs in the second div disappear.

For you convenience, you can copy the template from here, instead of typing it manually: ​http://pastebin.com/PFYj885M

If the paragraphs don't disappear after the first switch from text to visual, do it a couple of more times. I tried it on a fresh new install using the Twenty Sixteen theme.

I encountered this bug while having a couple of Instagram embeds on the same page, all of which loaded a script.