Avoid calling layout during flipNode.

Fixes #89943

src/vs/base/browser/ui/grid/gridview.ts

@@ -380,7 +380,7 @@ class BranchNode implements ISplitView<ILayoutContext>, IDisposable {
 			throw new Error('Invalid index');
 		}
 
-		this.splitview.addView(node, size, index);
+		this.splitview.addView(node, size, index, skipLayout);
 		this._addChild(node, index);
 		this.onDidChildrenChange();
 	}
@@ -791,7 +791,7 @@ function flipNode<T extends Node>(node: T, size: number, orthogonalSize: number)
 				newSize += size - totalSize;
 			}
 
-			result.addChild(flipNode(child, orthogonalSize, newSize), newSize, 0);
+			result.addChild(flipNode(child, orthogonalSize, newSize), newSize, 0, true);
 		}
 
 		return result as T;

src/vs/base/browser/ui/splitview/splitview.ts

@@ -331,8 +331,8 @@ export class SplitView<TLayoutContext = undefined> extends Disposable {
 		}
 	}
 
-	addView(view: IView<TLayoutContext>, size: number | Sizing, index = this.viewItems.length): void {
-		this.doAddView(view, size, index, false);
+	addView(view: IView<TLayoutContext>, size: number | Sizing, index = this.viewItems.length, skipLayout?: boolean): void {
+		this.doAddView(view, size, index, skipLayout);
 	}
 
 	removeView(index: number, sizing?: Sizing): IView<TLayoutContext> {