The Big Blue sky over 1925 Giants Drive had been replaced by a big black cloud when John Harbaugh’s Giants went to work Wednesday. 

Not every Giants player had heard that Jaxson Dart (MCL, PCL, meniscus damage) will undergo surgery and won’t be playing quarterback anymore this season, until Harbaugh broke the news at the team meeting. 

“The air just left the room,” Jon Runyan Jr. told The Post. 

Then Harbaugh moved swiftly to breathe life back into the room and into his team. Dart, a brace on his left knee, was in the meeting.