code: private void addAliasDeclarationNodes() {
      for (Entry<String, StringInfo> entry : stringInfoMap.entrySet()) {
        StringInfo info = entry.getValue();
        if (!info.isAliased) {
          continue;
        }
        String alias = info.getVariableName(entry.getKey());
        Node var = IR.var(IR.name(alias), IR.string(entry.getKey()));
        var.useSourceInfoFromForTree(info.parentForNewVarDecl);
        if (info.siblingToInsertVarDeclBefore == null) {
          info.parentForNewVarDecl.addChildToFront(var);
        } else {
          info.parentForNewVarDecl.addChildBefore(
              var, info.siblingToInsertVarDeclBefore);
        }
        compiler.reportChangeToEnclosingScope(var);
      }
    }
docs: Creates a var declaration for each aliased string. Var declarations are
  inserted as close to the first use of the string as possible.