getPrefix = function (context)
    {
        var vendors = [ 'i', 'webkitI', 'msI', 'mozI', 'oI' ];

        for (var i = 0; i < vendors.length; i++)
        {
            var s = vendors[i] + 'mageSmoothingEnabled';

            if (s in context)
            {
                return s;
            }
        }

        return null;
    }
Gets the Smoothing Enabled vendor prefix being used on the given context, or null if not set.

@function Phaser.Display.Canvas.Smoothing.getPrefix
@since 3.0.0

@param {(CanvasRenderingContext2D|WebGLRenderingContext)} context - The canvas context to check.

@return {string} The name of the property on the context which controls image smoothing (either `imageSmoothingEnabled` or a vendor-prefixed version thereof), or `null` if not supported.