delegateRequest not waiting for Remote Executor to resolve

[cajames]

When using a remote executor, in the Delegate module, the delegateRequest function fails to wait for promise resolution. This is caused by this line:

graphql-tools/packages/delegate/src/delegateToSchema.ts

Lines 165 to 168 in e6cb2c7

	if (executionResult instanceof Promise) {
	return executionResult.then(originalResult => transformer.transformResult(originalResult));
	}
	return transformer.transformResult(executionResult);

executionResult instanceof Promise returns false in Node 12.8.0. This issue has been faced elsewhere.

This causes all results from a remote schema to be null, and could lead to unhandled promise rejections.