fix(button): put host element into click event target (fix #89)

Author: Mikhail Bashkirov

packages/button/src/LionButton.js

@@ -159,9 +159,20 @@ export class LionButton extends DelegateMixin(SlotMixin(LionLitElement)) {
     oldEvent.stopPropagation();
     // replacing `MouseEvent` with `oldEvent.constructor` breaks IE
     const newEvent = new MouseEvent(oldEvent.type, oldEvent);
+    this.__enforceHostEventTarget(newEvent);
     this.$$slot('_button').dispatchEvent(newEvent);
   }
 
+  __enforceHostEventTarget(event) {
+    try {
+      // this is for IE11 (and works in others), because `Object.defineProperty` does not give any effect there
+      event.__defineGetter__('target', () => this); // eslint-disable-line no-restricted-properties
+    } catch (error) {
+      // in case `__defineGetter__` is removed from the platform
+      Object.defineProperty(event, 'target', { writable: false, value: this });
+    }
+  }
+
   __setupDelegation() {
     this.addEventListener('keydown', this.__keydownDelegationHandler);
     this.addEventListener('keyup', this.__keyupDelegationHandler);

packages/button/test/lion-button.test.js

@@ -194,6 +194,7 @@ describe('lion-button', () => {
         'cancelable',
         'clientX',
         'clientY',
+        'target',
       ];
 
       sameProperties.forEach(property => {