Beat egg whites and salt in a large bowl with mixer at high speed until soft peaks form.
Combine corn syrup and sugar in a small saucepan. Cook over medium-low heat, stirring constantly, until sugar dissolves and mixture comes to a full boil. Remove from heat.
Pour hot syrup into egg whites in a fine, steady stream while beating constantly. Beat in vanilla. Continue beating until mixture holds stiff peaks.
Use frosting immediately.
COCONUT FROSTING: Prepare Fluffy Frosting as above. Fold in 1 cup flaked coconut.