Fix reference to IGLTF

loaders/src/glTF/2.0/Extensions/KHR_lights.ts

@@ -105,7 +105,7 @@ module BABYLON.GLTF2.Extensions {
             });
         }
 
-        protected _loadRoot(loader: GLTFLoader, context: string, root: IGLTF): boolean {
+        protected _loadRoot(loader: GLTFLoader, context: string, root: BABYLON.GLTF2.IGLTF): boolean {
             return this._loadExtension<IKHRLights>(context, root, (context, extension, onComplete) => {
                 extension.lights.forEach((light: IGLTFLight, idx: number) => {
                     light.index = idx;

loaders/src/glTF/2.0/babylon.glTFLoaderExtension.ts

@@ -10,7 +10,7 @@ module BABYLON.GLTF2 {
 
         protected _loadNode(loader: GLTFLoader, context: string, node: IGLTFNode): boolean { return false; }
 
-        protected _loadRoot(loader: GLTFLoader, context: string, root: IGLTF): boolean { return false; }
+        protected _loadRoot(loader: GLTFLoader, context: string, root: BABYLON.GLTF2.IGLTF): boolean { return false; }
 
         protected _loadScene(loader: GLTFLoader, context: string, scene: IGLTFScene): boolean { return false; }
 
@@ -47,7 +47,7 @@ module BABYLON.GLTF2 {
             return this._ApplyExtensions(extension => extension._traverseNode(loader, context, node, action, parentNode));
         }
 
-        public static LoadRoot(loader: GLTFLoader, context: string, root: IGLTF): boolean {
+        public static LoadRoot(loader: GLTFLoader, context: string, root: BABYLON.GLTF2.IGLTF): boolean {
             return this._ApplyExtensions(extension => extension._loadRoot(loader, context, root));
         }