WebGLRenderer: Request extensions that shaders may need.

src/renderers/WebGLRenderer.js

@@ -220,10 +220,15 @@ THREE.WebGLRenderer = function ( parameters ) {
 			};
 
 		}
+
 	}
 
 	var extensions = new THREE.WebGLExtensions( _gl );
 
+	extensions.get( 'OES_texture_float' );
+	extensions.get( 'OES_texture_float_linear' );
+	extensions.get( 'OES_standard_derivatives' );
+
 	if ( _logarithmicDepthBuffer ) {
 
 		extensions.get( 'EXT_frag_depth' );