8024255: When a keyword is used as object property name, the property can not be deleted
Reviewed-by: jlaskey, lagergren
sealed? false
frozen? false
sealed? true
deleted num? false
num = 2.718281828459045
assign PI to num
num = 3.141592653589793
frozen? true
assign 1729 to num
num = 3.141592653589793