message: [logger] Flatten messageText when no file is provided in the diagnostic output.
  Fixes
diff: @@ -134,7 +134,7 @@ export class Logger {
  output += '(' + ts.getLineAndCharacterOfPosition(diagnostic.file, diagnostic.start).line + ')';
  output += ts.sys.newLine + ' ' + ts.flattenDiagnosticMessageText(diagnostic.messageText, ts.sys.newLine);
  } else {
  - output = diagnostic.messageText.toString();
  + output = ts.flattenDiagnosticMessageText(diagnostic.messageText, ts.sys.newLine);
  }
  switch (diagnostic.category) {
  