Update affix properly on scrollspy speedy scroll to top of page #11310

Fix scrollspy.js so as affix is updated properly when user scrolls fast
to top of page.

A fix for issue #11310.

dist/js/bootstrap.js

@@ -1665,6 +1665,10 @@ if (typeof jQuery === "undefined") { throw new Error("Bootstrap requires jQuery"
       return activeTarget != (i = targets.last()[0]) && this.activate(i)
     }
 
+    if (activeTarget && scrollTop <= offsets[0]) {
+      return activeTarget != (i = targets.first()[0]) && this.activate(i)
+    }
+
     for (i = offsets.length; i--;) {
       activeTarget != targets[i]
         && scrollTop >= offsets[i]

js/scrollspy.js

@@ -84,6 +84,10 @@
       return activeTarget != (i = targets.last()[0]) && this.activate(i)
     }
 
+    if (activeTarget && scrollTop <= offsets[0]) {
+      return activeTarget != (i = targets.first()[0]) && this.activate(i)
+    }
+
     for (i = offsets.length; i--;) {
       activeTarget != targets[i]
         && scrollTop >= offsets[i]