[Truffle] Introduce ImplicitCast from int to long.

* Only minimal changes required to make it compile.
[Truffle] Remove useless specializations for (int,int) on +,-,* always fitting long.
[Truffle] Fix bad return value for long * long without overflow.
[Truffle] Remove now useless (and incorrect!) AddNode specialization.

* Missing rewriteOn there.
[Truffle] Remove a useless AddNode specialization.

* Identical to the previous one.
[Truffle] Add with overflow should be SlowPath, otherwise it makes things much slower!

* for chunky-canvas-resampling-nearest-neighbor at least.