Pull request #267046: REPORT-114436 fix: tab设置single时内存泄露问题

Merge in DEC/fineui from ~SYLAR/fineui:release/11.0 to release/11.0

* commit '17a9e7ca7a0647fed1c988d4c65a5ba0854e3bbd':
  REPORT-114436 fix: tab设置single时内存泄露问题
  REPORT-101548 fix: 复选下拉树this指向问题

packages/fineui/src/core/wrapper/layout/layout.card.js

@@ -109,7 +109,10 @@ export class CardLayout extends Layout {
 
         const child = this._children[this._getChildName(cardName)];
         this._deleteCardByName(cardName);
-        child && child._destroy();
+        if (child) {
+            child._destroy();
+            child = null;
+        }
     }
 
     addCardByName(cardName, cardItem) {