Fix spooky errors due to closure and other unknowns TBD

Author: prushforth

src/map-feature.js

@@ -221,9 +221,9 @@ export class MapFeature extends HTMLElement {
     };
 
     let parentLayer =
-      parentEl.nodeName.toUpperCase() === 'LAYER-'
-        ? parentEl
-        : parentEl.parentElement || parentEl.parentNode.host;
+      this._parentEl.nodeName.toUpperCase() === 'LAYER-'
+        ? this._parentEl
+        : this._parentEl.parentElement || this._parentEl.parentNode.host;
     this._layer = parentLayer._layer;
     _attachedToMap();
   }

src/mapml/layers/MapMLLayer.js

@@ -1535,7 +1535,7 @@ export var MapMLLayer = L.Layer.extend({
           layer._styles = getAlternateStyles();
           layer._validateExtent();
           if (this.responseXML) {
-            attachToLayer();
+            attachToLayer.call(layer);
           }
           // update controls if needed based on mapml-viewer controls/controlslist attribute
           if (layer._layerEl.parentElement) {
@@ -1677,7 +1677,8 @@ export var MapMLLayer = L.Layer.extend({
         }
       }
       function attachToLayer() {
-        let shadowRoot = layer._layerEl.shadowRoot;
+        let mapml = xhr.responseXML,
+          shadowRoot = this._layerEl.shadowRoot;
         let elements = mapml.children[0].children[1].children;
         if (elements) {
           let baseURL = mapml.children[0].children[0]