Add shadycss to howto-tabs (#105)

Author: robdodson

elements/howto-tabs/howto-tabs.js

@@ -44,6 +44,11 @@
  <slot name="panel"></slot>
  `;
 
+ // HIDE
+ // ShadyCSS will rename classes as needed to ensure style scoping.
+ ShadyCSS.prepareTemplate(template, 'howto-tabs');
+ // /HIDE
+
  /**
  * `HowtoTabs` is a container element for tabs and panels.
  *
@@ -83,6 +88,13 @@
  * exactly one tab is active.
  */
  connectedCallback() {
+ // HIDE
+ // Shim Shadow DOM styles. This needs to be run in connectedCallback
+ // because if you shim Custom Properties (CSS variables) the element
+ // will need access to its parent node.
+ ShadyCSS.styleElement(this);
+ // /HIDE
+
  // The element needs to do some manual input event handling to allow
  // switching with arrow keys and Home/End.
  this.addEventListener('keydown', this._onKeyDown);