reST (reStructuredText) language can crash the browser

[nathf]

Information:

• Prism version: 1.16.0
• Environment: Browser, reproducible in Chrome (Version 75.0.3770.142 (Official Build) (64-bit)) & Firefox v67.0.4 - Build: 20190619235627

Does the latest version of Prism from the download page also have this issue? Yes

Description
On https://prismjs.com/test.html
Using the input string of

12345678901234567890123456897987987689567858756785765765675:a_a___

Then selecting the language reST (reStructuredText) causes the browser tab to hang, which I think is caused by:

prism/components/prism-rest.js

Line 189 in bab744a

pattern: /(?:\b[a-z\d](?:[_.:+]?[a-z\d]+)*_?_|`[^`]+`_?_|_`[^`]+`)(?=[\s\-.,:;!?\\\/'")\]}]|$)/i,