As far as I know, there's never been a court decision declaring that persons born citizens are "natural born citizens" for the sake of the Presidency.
Just as there's never been a court decision declaring that they aren't.
I challenge you to find one authoritative legal opinion in the entire history of the United States that says they are.
Okay.
"It is not necessary that a man should be born in this country, to be 'a natural born citizen.' It is only requisite that he should be a citizen by birth, and that is the case with all the children of citizens who have ever resided in this country, though born in a foreign country."
- James Bayard, A Brief Exposition of the Constitution of the United States (1834) (in the section on Presidential eligibility)
Bayard's doctrine - that men like Ted Cruz are explicitly ELIGIBLE to be President of the United States - was approved not just by Chief Justice John Marshall, but also by the legendary Justice Joseph Story, the also-famous Chancellor James Kent, "and other distinguished jurists:"
Another edition of this work having been called for, the author takes the opportunity of expressing his satisfaction with the manner in which his humble performance has been received. He has been much flattered by the favourable notice of Chief Justice Marshall, Judge Story, Chancellor Kent, and other distinguished jurists, who have done him the honor to communicate to him their approbation of the plan of the work, and the manner of its execution ; and express their opinion that it is well calculated for the attainment of the object for which it was intended. He begs leave to tender them his thanks for their kindness ; and having, in the present edition, corrected the only error of construction which has been pointed out to him, he hopes the work is now worthy of confidence as a guide in the construction of our admirable Constitution.
- "Advertisement" (what we might call a second Preface) to the Second Edition of Bayard's work (1840)
The "only error" in the original work that he refers to was a subtle error pointed out by Chief Justice Marshall. It was not anything remotely so glaring as declaring ineligible people eligible would have been:
The error alluded to was on page 70, of the former edition ; where it was stated, that the power of Congress extends to lay out military and post-roads, through the several States, "with their assent." Chief Justice Marshall, in a letter addressed to the author, expresses a doubt whether the assent of the States is requisite for the construction of post and militaryroads, which Congress is expressly authorized to make ; though such assent is necessary for other internal improvement ; and add, "with this exception, I do not recollect a single statement in your book which is not, in my my judgment, entirely just."
So there you have it. According to multiple major legal authorities of early America - Chief Justice John Marshall, the legendary Supreme Court Justice Joseph Story, the also-famous legal expert Chancellor James Kent, and "other distinguished jurists" - none of the rest of whom found any fault with James Bayard's exposition, either - it is not necessary that a person be born in the United States to be a "natural born citizen" and eligible to be President.
This proclamation also decisively shoots down the general birther claim that it takes two citizen parents plus birth on US soil to be a natural born citizen. And when we add the extremely clear words of William Rawle, as well as the opinion of St. George Tucker, I can't think of a single one of the really major early American legal experts who doesn't contradict the birther claim.
Bayard’s claim that “it is not necessary that a man should be born in this country, to be ‘a natural born citizen.’” is unsubstantiated and contradicted by law.
The Congress of 1790, many members of which were Framers, enacted law declaring children born out of country to citizens to be in law “natural born citizens”.
Congress in 1795 enacted law declaring children born out of country to citizens to be in law “citizens”.
The challenge was, that naturalized citizens are eligible. Bayard does not make this claim.
Bayard’s error is the claim that it is “not necessary that a man should be born in this country, to be ‘a natural born citizen.’”. He cites no law which supports this claim, a claim which in fact is contradicted by law: the citizenship of children born outside the United States to citizen parents has always depended upon operation of law, only during 1790-1795 were such children declared to be in law “natural born citizen”.