Fix #266

[zOadT]

This PR is split in 2 commits:

• The first one is the actual change needed for World step error #266
• The second one is about me getting too paranoid because of World step error #266. So feel free to discard it. Wanted to at least suggest it but in hindsight it seems unnecessary.

Note: #255 also often made use of the (mathematically correct) assumption that (A - B) . C == A . C - B . C. Technically this also changes the order of additions, but I guess this is probably fine.

[shakiba]

Looks good to me, thanks!

Just try it in the benchmark to make sure it doesn’t have unexpected impact on performance

[zOadT]

Good point! Ran 3x PR commit consecutively, 3x master commit consecutively and repeated this 3 times. Everything seems fine 👍

    fix: use combine operator order from box2d
Running Benchmarks:
 ✓ planck.js (current)

Results:
| Name                | avg ms/frame |           5th %ile |         95th %ile  | Ratio |
| ------------------- | ------------ | ------------------ | -----------------  | ----- |
| planck.js (current) |        12.94 | 11.798041999340057 | 14.33016699925065  |  1.00 |
| planck.js (current) |        13.01 | 11.887500001117587 | 14.298832999542356 |  1.00 |
| planck.js (current) |        13.18 | 12.029790999367833 | 14.547833999618888 |  1.00 |
| planck.js (current) |        12.83 | 11.65612499974668  | 14.266707999631763 |  1.00 |
| planck.js (current) |        13.22 | 12.081416999921203 | 14.534709000959992 |  1.00 |
| planck.js (current) |        13.02 | 11.900624999776483 | 14.34375           |  1.00 |
| planck.js (current) |        13.22 | 12.049542000517249 | 14.55120899900794  |  1.00 |
| planck.js (current) |        13.13 | 11.960750000551343 | 14.503916000947356 |  1.00 |
| planck.js (current) |        12.83 | 11.659291999414563 | 14.188333000987768 |  1.00 |


    fix setMassData
Running Benchmarks:
 ✓ planck.js (current)

Results:
| Name                | avg ms/frame |           5th %ile |          95th %ile | Ratio |
| ------------------- | ------------ | ------------------ | ------------------ | ----- |
| planck.js (current) |        13.54 | 12.306792000308633 | 14.869791999459267 |  1.00 |
| planck.js (current) |        13.14 | 11.965250000357628 | 14.521833000704646 |  1.00 |
| planck.js (current) |        12.92 | 11.742500001564622 | 14.336292000487447 |  1.00 |
| planck.js (current) |        13.09 | 11.844208000227809 | 14.573958000168204 |  1.00 |
| planck.js (current) |        12.92 | 11.737958000972867 | 14.373540999367833 |  1.00 |
| planck.js (current) |        12.91 | 11.786875000223517 | 14.235790999606252 |  1.00 |
| planck.js (current) |        12.92 | 11.671540999785066 | 14.627749999985099 |  1.00 |
| planck.js (current) |        13.63 | 12.491916000843048 | 14.934125000610948 |  1.00 |
| planck.js (current) |        13.32 | 12.188791001215577 | 14.714042000472546 |  1.00 |