chore(editor): remove redundant fields in viewport (#10569)

blocksuite/framework/block-std/src/gfx/viewport-element.ts

@@ -96,8 +96,6 @@ export class GfxViewportElement extends WithDisposable(ShadowlessElement) {
 
   private _updatingChildrenFlag = false;
 
-  renderingBlocks = new Set<string>();
-
   override connectedCallback(): void {
     super.connectedCallback();