message: Fix a bunch of recent DnD regressions
diff: @@ -45,7 +45,13 @@ export const FrameMimeType = {
  };
  function mimeTypeEquals(baseMimeType: string, mimeType: string, windowId: string): boolean {
  + const parts = mimeType.split(";");
  + const hasWindowId = parts.length !== 1 && parts[1].startsWith("windowid=");
  + if (windowId != null && hasWindowId) {
  return `${baseMimeType};windowid=${windowId}` === mimeType;
  + } else {
  + return baseMimeType === parts[0];
  + }
  }
  function dataTransferGetData(
  @@ -56,7 +62,7 @@ function dataTransferGetData(
  for (let i=0; i < dataTransfer.items.length; i++) {
  const item = dataTransfer.items[i];
  if (mimeType.equals(item.type, windowId)) {
  - dataTransfer.getData(item.type);
  + return dataTransfer.getData(item.type);
  }
  }
  return null;
  