WebGLProgram: Minor clean up.

src/renderers/webgl/WebGLProgram.js

@@ -280,7 +280,7 @@ THREE.WebGLProgram = ( function () {
 
 			prefixFragment = [
 
-				( parameters.bumpMap || parameters.normalMap || parameters.flatShading || material.derivatives ) ? '#extension GL_OES_standard_derivatives : enable' : '',
+				parameters.bumpMap || parameters.normalMap || parameters.flatShading || material.derivatives ? '#extension GL_OES_standard_derivatives : enable' : '',
 				parameters.logarithmicDepthBuffer && renderer.extensions.get( 'EXT_frag_depth' ) ? '#extension GL_EXT_frag_depth : enable' : '',
 
 				'precision ' + parameters.precision + ' float;',