code: void processScope(Scope scope) {
      boolean shouldAddToBlockStack = !scope.isHoistScope();
      this.narrowScope = scope;
      if (shouldAddToBlockStack) {
        blockStack.add(new BasicBlock(null, scope.getRootNode()));
      }
      (new NodeTraversal(compiler, this, scopeCreator)).traverseAtScope(scope);
      if (shouldAddToBlockStack) {
        pop(blockStack);
      }
      this.narrowScope = null;
    }
docs: Targets reference collection to a particular scope.