Changes based on review.

lib/utils/settings.js

@@ -8,15 +8,26 @@ Code distributed by Google as part of the polymer project is also
 subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
 */
 import './boot.js';
-
 import { pathFromUrl } from './resolve-url.js';
 export const useShadow = !(window.ShadyDOM) || !(window.ShadyDOM.inUse);
 export const useNativeCSSProperties = Boolean(!window.ShadyCSS || window.ShadyCSS.nativeCss);
 export const useNativeCustomElements = !(window.customElements.polyfillWrapFlushCallback);
 export const supportsAdoptingStyleSheets = useShadow &&
     ('adoptedStyleSheets' in Document.prototype) &&
-    ('replaceSync' in CSSStyleSheet.prototype);
-
+    ('replaceSync' in CSSStyleSheet.prototype) &&
+    // Since space may change, feature detect exact API we need
+    (() => {
+      try {
+        const sheet = new CSSStyleSheet();
+        sheet.replaceSync('');
+        const host = document.createElement('div');
+        host.attachShadow({mode: 'open'});
+        host.shadowRoot.adoptedStyleSheets = [sheet];
+        return (host.shadowRoot.adoptedStyleSheets[0] === sheet);
+      } catch(e) {
+        return false;
+      }
+    })();
 
 /**
  * Globally settable property that is automatically assigned to