Support no-argument constructors. Reviewed by Aryeh Gregor.
Support no-argument constructors.
Reviewed by Aryeh Gregor.

jyasskin/testharness.js,hallvors/testharness.js,zqzhang/testharness.js,jyasskin/testharness.js,RatneshThakur/testharness.js,hallvors/testharness.js,ayg/testharness.js,bboyle/testharness.js