add localization

Author: chrisirhc

assets/l10n/app_en.arb

@@ -43,6 +43,10 @@
   "@permissionsDeniedReadExternalStorage": {
     "description": "Message for dialog asking the user to grant permissions for external storage read access."
   },
+  "actionSheetOptionAddReaction": "Add reaction",
+  "@actionSheetOptionAddReaction":  {
+    "description": "Label for add reaction button on action sheet."
+  },
   "actionSheetOptionCopy": "Copy message text",
   "@actionSheetOptionCopy":  {
     "description": "Label for copy message text button on action sheet."
@@ -67,6 +71,10 @@
   "@errorCouldNotFetchMessageSource": {
     "description": "Error message when the source of a message could not be fetched."
   },
+  "errorAddingReactionFailed": "Adding a reaction failed",
+  "@errorAddingReactionFailed": {
+    "description": "Error message when adding a reaction to a message failed."
+  },
   "errorCopyingFailed": "Copying failed",
   "@errorCopyingFailed": {
     "description": "Error message when copying the text of a message to the user's system clipboard failed."

lib/widgets/action_sheet.dart

@@ -87,7 +87,7 @@ class AddReactionButton extends MessageActionSheetMenuItemButton {
 
   @override
   String label(ZulipLocalizations zulipLocalizations) {
-    return 'Add reaction'; // TODO(i18n) skip translation for now
+    return zulipLocalizations.actionSheetOptionAddReaction;
   }
 
   @override get onPressed => (BuildContext context) async {
@@ -135,8 +135,9 @@ class AddReactionButton extends MessageActionSheetMenuItemButton {
                   default:
                 }
 
+                final zulipLocalizations = ZulipLocalizations.of(messageListContext);
                 await showErrorDialog(context: emojiPickerContext,
-                  title: 'Adding reaction failed', message: errorMessage);
+                  title: zulipLocalizations.errorAddingReactionFailed, message: errorMessage);
               }
             }));
       });