fix: Fixed ungrouping a folder not updating the last saved group, b=no-bug, c=no-component

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

@@ -1,5 +1,5 @@
 diff --git a/browser/components/tabbrowser/content/tabgroup.js b/browser/components/tabbrowser/content/tabgroup.js
-index caea196b22b4689f55780a528661d87b52f4e728..9c1e141b6b2121d32f30c82862b597146f664b34 100644
+index caea196b22b4689f55780a528661d87b52f4e728..c107c803d0820a209c0859745dcc8370294eb7b2 100644
 --- a/browser/components/tabbrowser/content/tabgroup.js
 +++ b/browser/components/tabbrowser/content/tabgroup.js
 @@ -13,10 +13,12 @@
@@ -18,7 +18,7 @@ index caea196b22b4689f55780a528661d87b52f4e728..9c1e141b6b2121d32f30c82862b59714
        <vbox class="tab-group-overflow-count-container" pack="center">
          <label class="tab-group-overflow-count" role="button" />
        </vbox>
-@@ -57,20 +59,26 @@
+@@ -57,20 +59,28 @@
      }
  
      connectedCallback() {
@@ -30,6 +30,8 @@ index caea196b22b4689f55780a528661d87b52f4e728..9c1e141b6b2121d32f30c82862b59714
 +            detail: this,
 +          })
 +        );
++      } else if (!this.group) {
++        this._lastGroup = null;
 +      }
        // Always set the mutation observer to listen for tab change events, even
        // if we are already initialized.
@@ -49,7 +51,7 @@ index caea196b22b4689f55780a528661d87b52f4e728..9c1e141b6b2121d32f30c82862b59714
  
        this._initialized = true;
        this.saveOnWindowClose = true;
-@@ -97,11 +105,14 @@
+@@ -97,11 +107,14 @@
        this.#labelElement.container = gBrowser.tabContainer;
        this.#labelElement.group = this;
  
@@ -69,7 +71,7 @@ index caea196b22b4689f55780a528661d87b52f4e728..9c1e141b6b2121d32f30c82862b59714
  
        this.#updateLabelAriaAttributes();
        this.#updateCollapsedAriaAttributes();
-@@ -127,6 +138,8 @@
+@@ -127,6 +140,8 @@
        // mounts after getting created by `Tabbrowser.adoptTabGroup`.
        this.#wasCreatedByAdoption = false;
      }
@@ -78,7 +80,7 @@ index caea196b22b4689f55780a528661d87b52f4e728..9c1e141b6b2121d32f30c82862b59714
  
      resetDefaultGroupName = () => {
        this.#defaultGroupName = "";
-@@ -197,7 +210,10 @@
+@@ -197,7 +212,10 @@
            }
          });
        }
@@ -90,7 +92,7 @@ index caea196b22b4689f55780a528661d87b52f4e728..9c1e141b6b2121d32f30c82862b59714
      }
  
      get color() {
-@@ -338,12 +354,61 @@
+@@ -338,12 +356,61 @@
            tabGroupName,
          })
          .then(result => {
@@ -154,7 +156,7 @@ index caea196b22b4689f55780a528661d87b52f4e728..9c1e141b6b2121d32f30c82862b59714
      }
  
      /**
-@@ -373,7 +438,7 @@
+@@ -373,7 +440,7 @@
       */
      addTabs(tabs, metricsContext) {
        for (let tab of tabs) {
@@ -163,7 +165,7 @@ index caea196b22b4689f55780a528661d87b52f4e728..9c1e141b6b2121d32f30c82862b59714
            tab.ownerGlobal.gBrowser.unpinTab(tab);
          }
          let tabToMove =
-@@ -437,7 +502,7 @@
+@@ -437,7 +504,7 @@
       */
      on_click(event) {
        let isToggleElement =
@@ -172,7 +174,7 @@ index caea196b22b4689f55780a528661d87b52f4e728..9c1e141b6b2121d32f30c82862b59714
          event.target === this.#overflowCountLabel;
        if (isToggleElement && event.button === 0) {
          event.preventDefault();
-@@ -470,5 +535,6 @@
+@@ -470,5 +537,6 @@
      }
    }