fix: dragging and disposing of shadows (#8172)

* Revert "fix: dragging blocks by shadows to delete (#8138)"

This reverts commit 3fd749205f.

* fix: dragging shadows

core/block.ts

@@ -675,17 +675,6 @@ export class Block implements IASTNodeLocation {
     return block;
   }
 
-  /**
-   * Returns this block if it is a shadow block, or the first non-shadow parent.
-   *
-   * @internal
-   */
-  getFirstNonShadowBlock(): this {
-    if (!this.isShadow()) return this;
-    // We can assert the parent is non-null because shadows must have parents.
-    return this.getParent()!.getFirstNonShadowBlock();
-  }
-
   /**
    * Find all the blocks that are directly nested inside this one.
    * Includes value and statement inputs, as well as any following statement.