Create debugger html compare URL

debugger-html_create-compare-url.js

async function createCompareURL(attachmentUrl) {
  let attachment = await fetch(attachmentUrl);
  let patch = await attachment.text();
  let oldHash = patch.match(/\-Taken from upstream commit: ([a-f0-9]+)\n/)[1];
  let newHash = patch.match(/\+Taken from upstream commit: ([a-f0-9]+)\n/)[1];

  let compareUrl = 
    `https://github.com/devtools-html/debugger.html/compare/${oldHash}...${newHash}`;
  console.log(compareUrl);
} 

createCompareURL("https://bug1427187.bmoattachments.org/attachment.cgi?id=8938964");