contractor.js: Get rid of run-with-delay

[alainbryden]

The custom script run-with-delay is a needlessly complex step since many API functions became cheaper.

The run-with-delay footprint is 2.6 GB, but if we just directly invoked contractor.js.solver.js from contractor.js, whose ram footprint is 2.8 GB, the overall increase in peak memory footprint is a mere 0.2 GB. This doesn't seem worth the increase in complexity