hasExt = function (gl, format)
        {
            var results = gl.getExtension(extString + format) || gl.getExtension(wkExtString + format) || gl.getExtension(extEXTString + format);

            if (results)
            {
                var glEnums = {};

                for (var key in results)
                {
                    glEnums[results[key]] = key;
                }

                return glEnums;
            }
        }
Determines which compressed texture formats this browser and device supports.

Called automatically as part of the WebGL Renderer init process. If you need to investigate
which formats it supports, see the `Phaser.Renderer.WebGL.WebGLRenderer#compression` property instead.

@method Phaser.Renderer.WebGL.WebGLRenderer#getCompressedTextures
@since 3.60.0

@return {Phaser.Types.Renderer.WebGL.WebGLTextureCompression} The compression object.