Skip one unnecessary global traversal of source and externs in the let/const rewriting pass.

Since the let/const rewriting pass now runs post-normalize, it need not run the MakeDeclaredNamesUnique renamer across the entire source and externs. This saves the cost of 1 full traversal on the unoptimized source+externs AST.

PiperOrigin-RevId: 621147152

Author: rishipal

src/com/google/javascript/jscomp/Es6RewriteBlockScopedDeclaration.java

@@ -86,10 +86,8 @@ public void visit(NodeTraversal t, Node n, Node parent) {
 
   @Override
   public void process(Node externs, Node root) {
-    // Make all declared names unique, so we can safely just switch 'let' or 'const' to 'var' in all
-    // non-loop cases.
-    MakeDeclaredNamesUnique renamer = MakeDeclaredNamesUnique.builder().build();
-    NodeTraversal.traverseRoots(compiler, renamer, externs, root);
+    // All declared names are already unique post normalize, so we can safely just switch 'let' or
+    // 'const' to 'var' in all non-loop cases.
     // - Gather a list of let & const variables
     // - Also add `= void 0` to any that are not initialized.
     NodeTraversal.traverse(compiler, root, this);