decouple PerspectiveCamera parameters in ObjectLoader (#8599)

* decouple PerspectiveCamera parameters in ObjectLoader. see comment: https://github.com/mrdoob/three.js/pull/8561/files/7eea5d47d86a6376175761cddab2742f17de177f#r59205742

* null -> undefined checking of data.view

* only export view if defined.

src/cameras/PerspectiveCamera.js

@@ -215,7 +215,8 @@ THREE.PerspectiveCamera.prototype.toJSON = function( meta ) {
 	data.object.focus = this.focus;
 
 	data.object.aspect = this.aspect;
-	data.object.view = this.view === null ? null : Object.assign( {}, this.view );
+	
+	if( this.view ) data.object.view = Object.assign( {}, this.view );
 
 	data.object.filmGauge = this.filmGauge;
 	data.object.filmOffset = this.filmOffset;

src/loaders/ObjectLoader.js

@@ -471,16 +471,9 @@ THREE.ObjectLoader.prototype = {
 
 					if ( data.focus !== undefined ) object.focus = data.focus;
 					if ( data.zoom !== undefined ) object.zoom = data.zoom;
-
-					if ( data.filmGauge !== undefined ) {
-
-						if ( data.view !== null )
-							object.view = Object.assign( {}, data.view );
-
-						object.filmGauge = data.filmGauge;
-						object.filmOffset = data.filmOffset;
-
-					}
+					if ( data.filmGauge !== undefined ) object.filmGauge = data.filmGauge;
+					if ( data.filmOffset !== undefined ) object.filmOffset = data.filmOffset;
+					if ( data.view !== undefined ) object.view = Object.assign( {}, data.view );
 
 					break;