Function boa::builtins::string::last_index_of

pub fn last_index_of(
    this: &Value, 
    args: &[Value], 
    ctx: &mut Interpreter
) -> ResultValue

object to a String at one or more indices that are smaller than or equal to position, then the greatest such index is returned; otherwise, -1 is returned. If position is undefined, the length of the String value is assumed, so as to search all of the String. https://tc39.github.io/ecma262/#sec-string.prototype.lastindexof