Support removing trends widgets without cogwheel (#1)

Some users are reporting a version of the trends widget without the
cogwheel link. We can try to identify this version (also the other
version, but let’s keep the old code for that) using the “trending
with…” links under some trends, which, if they exist, identify the
source via some URL parameters.

hide-twitter-trends.js

@@ -6,6 +6,12 @@
  * then look at some of the neighboring DOM trying to reduce false positives.
  * (The many class names on the elements don’t look stable,
  * so we only match on element names, hoping they’re more reliable.)
+ *
+ * There is also a version of the Trends widget without the cogwheel.
+ * We can try to identify this using the “trending with…” links,
+ * which, if they exist, have &src=trend_click in the URL.
+ * (The actual trends themselves aren’t links at all, but divs with event handlers.)
+ * If none of the trends are “trending with” something, we’re out of luck.
  */
 function removeTrends() {
     for (let trends of document.querySelectorAll('a[href="/settings/trends"]')) {
@@ -32,6 +38,29 @@ function removeTrends() {
             trends = parent;
         trends.remove();
     }
+    for (let trends of document.querySelectorAll('a[href*="&src=trend_click"]')) {
+        if (!document.body.contains(trends)) {
+            // we already removed the parent trends widget
+            continue;
+        }
+        if (trends.closest('article')) {
+            // trends link in a tweet
+            continue;
+        }
+        trends = trends.closest('section');
+        if (!trends) {
+            // (unclear if this can happen)
+            continue;
+        }
+        if (trends.firstElementChild.tagName !== 'H1') {
+            // (unclear if this can happen)
+            continue;
+        }
+        let parent;
+        while ((parent = trends.parentElement).childElementCount == 1)
+            trends = parent;
+        trends.remove();
+    }
 }
 
 setTimeout(removeTrends, 3 * 1000);