Fix typing Chinese in Edge (facebookarchive#2082) (facebookarchive#2088)

Summary:
Fixes facebookarchive#2082.
Pull Request resolved: facebookarchive#2088

Differential Revision: D18698264

Pulled By: mrkev

fbshipit-source-id: f5f5d4e4a0ff66a9fef62976af8726660411a106

Author: robbertbrak

src/component/handlers/composition/DOMObserver.js

@@ -113,14 +113,19 @@ class DOMObserver {
         return target.textContent;
       }
     } else if (type === 'childList') {
-      // `characterData` events won't happen or are ignored when
-      // removing the last character of a leaf node, what happens
-      // instead is a `childList` event with a `removedNodes` array.
-      // For this case the textContent should be '' and
-      // `DraftModifier.replaceText` will make sure the content is
-      // updated properly.
       if (removedNodes && removedNodes.length) {
+        // `characterData` events won't happen or are ignored when
+        // removing the last character of a leaf node, what happens
+        // instead is a `childList` event with a `removedNodes` array.
+        // For this case the textContent should be '' and
+        // `DraftModifier.replaceText` will make sure the content is
+        // updated properly.
         return '';
+      } else if (target.textContent !== '') {
+        // Typing Chinese in an empty block in MS Edge results in a
+        // `childList` event with non-empty textContent.
+        // See https://github.com/facebook/draft-js/issues/2082
+        return target.textContent;
       }
     }
     return null;

src/component/handlers/composition/__tests__/DraftEditorCompostionHandler-test.js

@@ -67,7 +67,7 @@ function getEditorStateFromHTML(html: string) {
   const state =
     blocksFromHTML != null
       ? ContentState.createFromBlockArray(
-          blocksFromHTML.contentBlocks ?? [],
+          blocksFromHTML.contentBlocks || [],
           blocksFromHTML.entityMap,
         )
       : ContentState.createEmpty();