There are three contractors that I can think of that do Disney's big theme park projects...
Balfour Beatty - Currently doing Avatarland and other projects at AK.
Whiting Turner - Currently doing Frozen at Epcot and TSMM at DHS.
H O A R Construction - Currently finishing the hub. They are also the contractor who did Fantastyland.
Even though Whiting Turner is doing TSMM, I am leaning towards H O A R since they currently don't have a big project in the works with Disney. They could also use multiple contractors, maybe Whiting does TSL, and H O A R does SWL and/or infrastrucutre.