Add innerText field to Element class

As mentioned in #28303 Dart needs the innerText getter/setter.

This seems like all thats needed.

Closes #35471
https://github.com/dart-lang/sdk/pull/35471

GitOrigin-RevId: 95f45dd8ba1d0ce58acbeb99242c45b56c586f85
Change-Id: I3514e02915b4c388d6fe2462976e0a88a6081493
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/100822
Reviewed-by: Johnni Winther <johnniwinther@google.com>
Commit-Queue: Michael Thomsen <mit@google.com>
diff --git a/sdk/lib/html/dart2js/html_dart2js.dart b/sdk/lib/html/dart2js/html_dart2js.dart
index 656fa6b..eb75be5 100644
--- a/sdk/lib/html/dart2js/html_dart2js.dart
+++ b/sdk/lib/html/dart2js/html_dart2js.dart
@@ -13944,6 +13944,8 @@
   @JSName('innerHTML')
   String _innerHtml;
 
+  String innerText;
+
   @JSName('localName')
   final String _localName;