You don't need 900 million of American money to rebuild Gaza. Just get a couple hundred Israeli tanks to do the redecorating for you.
Seriously this has to be the dumbest idea I've ever heard.
#1 Yes, the Israelis will just blow it up again
#2 Who's going to do the building? locals will end up sending the money to fund Hamas who has a huge support base in Gaza, or if it it's foreign contractors you can expect a rash of kidnappings, beheading... etc..
Let Egypt foot the bill, or Germany, or some other wishy washy Eurotrash countries that like to practice appeasement.