fix: Fixed new tabs opening where pinned tabs are when creating a split view, b=closes #9014, c=no-component

Author: mr-cheffy

src/browser/components/tabbrowser/content/tabbrowser-js.patch

@@ -1,5 +1,5 @@
 diff --git a/browser/components/tabbrowser/content/tabbrowser.js b/browser/components/tabbrowser/content/tabbrowser.js
-index d5aa64842a35c6697263c63fd3a0571b64b01344..478050fd5202b70ee3191471a017e091a3a87e92 100644
+index d5aa64842a35c6697263c63fd3a0571b64b01344..031b384c848fd391f84ed1e6d4f991f3287e37a4 100644
 --- a/browser/components/tabbrowser/content/tabbrowser.js
 +++ b/browser/components/tabbrowser/content/tabbrowser.js
 @@ -413,11 +413,41 @@
@@ -9,7 +9,7 @@ index d5aa64842a35c6697263c63fd3a0571b64b01344..478050fd5202b70ee3191471a017e091
 +    get _numVisiblePinTabsWithoutCollapsed() {
 +      let i = 0;
 +      for (let item of this.tabContainer.ariaFocusableItems) {
-+        if (this.isTabGroupLabel(item) && item.closest("zen-folder")?.pinned) {
++        if (this.isTabGroupLabel(item) && item.closest("zen-group")?.pinned) {
 +          i += 1;
 +          continue;
 +        }