Appears to be working in Firefox but at least Chrome & Safari are broken. Should be a really recent regression so very few possible changes to blame...

Easiest repo: the todo list on our homepage.

CONTENT_TYPES[typeof props.children] ? props.children : null;
      var childrenToUse = contentToUse != null ? null : props.children;
      if (contentToUse != null) {
        
        ret = escapeTextContentForBrowser(contentToUse);
      } else if (childrenToUse != null) {
        var mountImages = this.mountChildren(
          childrenToUse,
          transaction,
          context
        );
        ret = mountImages.join('');
      }
    }
    if (newlineEatingTags[this._tag] && ret.charAt(0) === '\n') {
      
      
      
      
      
      
      
      
      
      
      return '\n' + ret;
    } else {
      return ret;
    }
  },