Review

class Normalize {
  @Override
  public void process(Node externs, Node root) {
    NodeTraversal.traverse(compiler, root,
        new NormalizeStatements(compiler, assertOnChange));
    if (MAKE_LOCAL_NAMES_UNIQUE) {
      MakeDeclaredNamesUnique renamer = new MakeDeclaredNamesUnique();
      NodeTraversal t = new NodeTraversal(compiler, renamer);
      t.traverseRoots(externs, root);
    }
    // It is important that removeDuplicateDeclarations runs after
    // MakeDeclaredNamesUnique in order for catch block exception names to be
    // handled properly. Specifically, catch block exception names are
    // only valid within the catch block, but our currect Scope logic
    // has no concept of this and includes it in the containing function
    // (or global scope). MakeDeclaredNamesUnique makes the catch exception
    // names unique so that removeDuplicateDeclarations() will properly handle
    // cases where a function scope variable conflict with a exception name:
    //   function f() {
    //      try {throw 0;} catch(e) {e; /* catch scope 'e'*/}
    //      var e = 1; // f scope 'e'
    //   }
    // otherwise 'var e = 1' would be rewritten as 'e = 1'.
    // TODO(johnlenz): Introduce a seperate scope for catch nodes.
    removeDuplicateDeclarations(externs, root);
    new PropagateConstantAnnotationsOverVars(compiler, assertOnChange)
        .process(externs, root);

    if (!compiler.getLifeCycleStage().isNormalized()) {
      compiler.setLifeCycleStage(LifeCycleStage.NORMALIZED);
    }
  }
}

class Normalize.PropagateConstantAnnotationsOverVars {
    @Override
    public void process(Node externs, Node root) {
      new NodeTraversal(compiler, this).traverseRoots(externs, root);
    }
}

class Normalize.VerifyConstants {
    @Override
    public void process(Node externs, Node root) {
      Node externsAndJs = root.getParent();
      Preconditions.checkState(externsAndJs != null);
      Preconditions.checkState(externsAndJs.hasChild(externs));

      NodeTraversal.traverseRoots(
          compiler, Lists.newArrayList(externs, root), this);
    }

}