Fix the tests of tf.profile

[Linchenn]

The tf.profile()'s tests expect the kernelTimeMs and extraInfo have been resolved from Promise, but the kernelTimeMs in tf.profile()'s return value can not only be number type, but also {error: string}, as:

type KernelInfo = {
  ...
  kernelTimeMs: number | {error: string} | Promise<number|{error: string}>;
  extraInfo: string | Promise<string>;
};

(at https://github.com/tensorflow/tfjs/blob/master/tfjs-core/src/engine.ts#L55)

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