function compileShader(gl, type, src) {
    var shader = gl.createShader(type);
    gl.shaderSource(shader, src);
    gl.compileShader(shader);
    return shader;
}
@private
@param {WebGLRenderingContext} gl - The current WebGL context {WebGLProgram}
@param {number} type - the type, can be either VERTEX_SHADER or FRAGMENT_SHADER
@param {string} src - The vertex shader source as an array of strings.
@returns {WebGLShader} the shader