Adds float v int test.
Corrects Array.prototype.splice delete exceeding len. Fixes #611
Adds test for #612.
Updates most tests to be conforming to TAP.
Repairs http.js test to succeed on Node.
Adds proper float generation to floatint.js test.
Merge #615 r=@tcr: Updates tests to be mostly TAP compliant. Adds a few tests. One Array fix.

This PR adds a few fixes and repairs tests to run through tinytap, needed for the runtime-qemu rig (and general correctness).

* Updates all non-tap-compliant runtime tests to be TAP compliant, anticipating a switch to tinytap for runtime tests (as it is in runtime-qemu rig)
* Adds / refactors a few tests.
* Fixes an Array splice bug on master.