perf(linter/plugins): speed up SourceCode#getAncestors (#14747)

Optimize `SourceCode#getAncestors`:

* Remove temp var `ancestor`.
* Reduce code repetition.
* Check for end of loop with `=== null` (instead of truthiness test).

Author: overlookmotel

apps/oxlint/src-js/plugins/source_code.ts

@@ -520,12 +520,10 @@ export type SourceCode = typeof SOURCE_CODE;
 function getAncestors(node: Node): Node[] {
   const ancestors = [];
 
-  for (
-    let ancestor = (node as unknown as { parent: Node }).parent;
-    ancestor;
-    ancestor = (ancestor as unknown as { parent: Node }).parent
-  ) {
-    ancestors.push(ancestor);
+  while (true) {
+    node = (node as unknown as { parent: Node }).parent;
+    if (node === null) break;
+    ancestors.push(node);
   }
 
   return ancestors.reverse();