Remove unused readwrite annotation for .task property of TaskCompletionSource.
Remove unused readwrite annotation for .task property of TaskCompletionSource.

dbarabander/Bolts-iOS,dbarabander/Bolts-iOS,BoltsFramework/Bolts-iOS,BoltsFramework/Bolts-iOS,BoltsFramework/Bolts-iOS,dbarabander/Bolts-iOS