fix: apply workaround to pass tests in Safari 10

src/vaadin-rich-text-editor.html

@@ -417,6 +417,29 @@
           ];
         }
 
+        /**
+         * @protected
+         */
+        attributeChangedCallback(prop, oldVal, newVal) {
+          super.attributeChangedCallback(prop, oldVal, newVal);
+          // Needed until Edge has CSS Custom Properties (present in Edge Preview)
+          /* istanbul ignore if */
+          if (/^(readonly|disabled|theme)$/.test(prop)) {
+            // iOS 10.3 Safari has an issue with repainting shadow root element styles when a host attribute changes.
+            // Need this workaround (toggle any inline css property on and off) until we drop iOS 10.
+            const isIOS = /iPad|iPhone|iPod/.test(navigator.userAgent) && !window.MSStream;
+
+            /* istanbul ignore if */
+            if (isIOS && this.shadowRoot && parseInt(navigator.appVersion.match(/OS (\d+)_(\d+)_?(\d+)?/)[1], 10)) {
+              const WEBKIT_PROPERTY = '-webkit-backface-visibility';
+              this.shadowRoot.querySelectorAll('*').forEach(el => {
+                el.style[WEBKIT_PROPERTY] = 'visible';
+                el.style[WEBKIT_PROPERTY] = '';
+              });
+            }
+          }
+        }
+
         ready() {
           super.ready();