WebGLShadowMap: Use LinearFilter instead.

src/renderers/webgl/WebGLShadowMap.js

@@ -160,7 +160,7 @@ THREE.WebGLShadowMap = function ( _renderer, _lights, _objects ) {
 
 			if ( shadow.map === null ) {
 
-				var pars = { minFilter: THREE.NearestFilter, magFilter: THREE.NearestFilter, format: THREE.RGBAFormat };
+				var pars = { minFilter: THREE.LinearFilter, magFilter: THREE.LinearFilter, format: THREE.RGBAFormat };
 
 				shadow.map = new THREE.WebGLRenderTarget( shadowMapSize.x, shadowMapSize.y, pars );