fix: Add a plugin to fix the last column in a table (#7036)

shared/editor/lib/changedDescendants.ts

@@ -0,0 +1,37 @@
+import { Node } from "prosemirror-model";
+
+/**
+ * Helper for iterating through the nodes in a document that changed
+ * compared to the given previous document. Useful for avoiding
+ * duplicate work on each transaction.
+ */
+export function changedDescendants(
+  /** The previous node */
+  old: Node,
+  /** The current node */
+  cur: Node,
+  /** The offset of the current node */
+  offset: number,
+  /** The function to call for each changed node */
+  callback: (node: Node, pos: number) => void
+): void {
+  const oldSize = old.childCount,
+    curSize = cur.childCount;
+  outer: for (let i = 0, j = 0; i < curSize; i++) {
+    const child = cur.child(i);
+    for (let scan = j, e = Math.min(oldSize, i + 3); scan < e; scan++) {
+      if (old.child(scan) === child) {
+        j = scan + 1;
+        offset += child.nodeSize;
+        continue outer;
+      }
+    }
+    callback(child, offset);
+    if (j < oldSize && old.child(j).sameMarkup(child)) {
+      changedDescendants(old.child(j), child, offset + 1, callback);
+    } else {
+      child.nodesBetween(0, child.content.size, callback, offset + 1);
+    }
+    offset += child.nodeSize;
+  }
+}