WebGLRenderer: Avoid 0 shininess. Fixes #7252.

src/renderers/WebGLRenderer.js

@@ -1880,7 +1880,7 @@ THREE.WebGLRenderer = function ( parameters ) {
 	function refreshUniformsPhong ( uniforms, material ) {
 
 		uniforms.specular.value = material.specular;
-		uniforms.shininess.value = material.shininess;
+		uniforms.shininess.value = Math.max( material.shininess, 1e-4 );
 
 		if ( material.lightMap ) {