glsl.js: Clean up

src/renderers/shaders/ShaderChunk/dithering_fragment.glsl.js

 export default /* glsl */`
 #if defined( DITHERING )
 
-  gl_FragColor.rgb = dithering( gl_FragColor.rgb );
+	gl_FragColor.rgb = dithering( gl_FragColor.rgb );
 
 #endif
 `;

src/renderers/shaders/ShaderChunk/encodings_fragment.glsl.js

 export default /* glsl */`
-  gl_FragColor = linearToOutputTexel( gl_FragColor );
+gl_FragColor = linearToOutputTexel( gl_FragColor );
 `;

src/renderers/shaders/ShaderChunk/tonemapping_fragment.glsl.js

 export default /* glsl */`
 #if defined( TONE_MAPPING )
 
-  gl_FragColor.rgb = toneMapping( gl_FragColor.rgb );
+	gl_FragColor.rgb = toneMapping( gl_FragColor.rgb );
 
 #endif
 `;