Fix protoplanet example

https://github.com/mrdoob/three.js/issues/13293

examples/webgl_gpgpu_protoplanet.html

@@ -277,7 +277,7 @@
 			if ( hash ) hash = parseInt( hash, 0 );
 
 			// Texture width for simulation (each texel is a debris particle)
-			var WIDTH = hash || ( isIE || isEdge ) ? 4 : 64;
+			var WIDTH = hash || ( ( isIE || isEdge ) ? 4 : 64 );
 
 			var container, stats;
 			var camera, scene, renderer, geometry, controls;