UppercaseFirst = function (str)
{
    return str && str[0].toUpperCase() + str.slice(1);
}
Capitalizes the first letter of a string if there is one.
@example
UppercaseFirst('abc');
// returns 'Abc'
@example
UppercaseFirst('the happy family');
// returns 'The happy family'
@example
UppercaseFirst('');
// returns ''

@function Phaser.Utils.String.UppercaseFirst
@since 3.0.0

@param {string} str - The string to capitalize.

@return {string} A new string, same as the first, but with the first letter capitalized.