Bring back K2 tab

src/css/content.scss

@@ -743,12 +743,20 @@ $color-dark-yellow: #DAA520;
 li.k2-extension {
     display: flex;
     align-items: center;
+    list-style: none;
+}
+
+// Prevent the isolated K2 tab from covering GitHub's next tab.
+nav[aria-label="Repository"] a[href*="/pulls"] {
+    margin-right: 48px;
 }
 
 .k2-nav-link {
     display: flex;
     align-items: center;
-    padding: 8px 16px;
+    box-sizing: border-box;
+    height: 100%;
+    padding: 0 8px;
     font-size: 14px;
     font-weight: 400;
     line-height: 1.5;

src/js/lib/pages/github/all.js

@@ -1,4 +1,6 @@
+import $ from 'jquery';
 import Base from './_base';
+import k2Button from '../../../template/button.github.k2.html';
 
 /**
  * This class manages the things that happen on *every* GitHub page. All it's doing is adding links to the
@@ -17,6 +19,41 @@ export default function () {
      * Add buttons to the page and setup the event handler
      */
     AllPages.setup = function () {
+        let k2Tab = $('li.k2-extension');
+
+        if (!k2Tab.length) {
+            // Keep the K2 tab outside GitHub's managed list because inserting it into that list breaks search.
+            $('body').append(k2Button({url: '/Expensify/Expensify'}));
+            k2Tab = $('li.k2-extension');
+        }
+
+        const positionK2Tab = () => {
+            const pullsTab = $('nav[aria-label="Repository"] a[href*="/pulls"]').first();
+
+            if (!pullsTab.length) {
+                k2Tab.hide();
+                return;
+            }
+
+            // Use the Pull requests position so the isolated K2 tab looks like part of GitHub's tab list.
+            const rectangle = pullsTab[0].getBoundingClientRect();
+            k2Tab.css({
+                display: 'flex',
+                position: 'fixed',
+                top: rectangle.top,
+                left: rectangle.right + 8,
+                height: rectangle.height,
+                zIndex: 1000,
+            });
+        };
+
+        positionK2Tab();
+
+        // Keep the isolated tab aligned when the window moves GitHub's tab list.
+        $(window)
+            .off('resize.k2-extension scroll.k2-extension')
+            .on('resize.k2-extension scroll.k2-extension', positionK2Tab);
+
         // Set up timestamp format conversion
         setTimeout(() => AllPages.applyTimestampFormat(), 500);
         setInterval(() => AllPages.applyTimestampFormat(), 5000);