RenderNodes: Fix context.material reference. (mrdoob#26838)

Author: sunag

examples/jsm/renderers/common/nodes/Nodes.js

@@ -40,6 +40,7 @@ class Nodes extends DataMap {
 
 				const nodeBuilder = this.backend.createNodeBuilder( renderObject.object, this.renderer, renderObject.scene );
 				nodeBuilder.material = renderObject.material;
+				nodeBuilder.context.material = renderObject.material;
 				nodeBuilder.lightsNode = renderObject.lightsNode;
 				nodeBuilder.environmentNode = this.getEnvironmentNode( renderObject.scene );
 				nodeBuilder.fogNode = this.getFogNode( renderObject.scene );