Render masks to constant lists.

[modulovalue]

Consider the _bitMask and _clearMask masks:

final _bitMask = List<int>.generate(32, (i) => 1 << i);
final _clearMask = List<int>.generate(32, (i) => ~(1 << i));

We can bake them into constant lists:

// print("const _bitMask = [${List<int>.generate(32, (i) => 1 << i).join(", ")}];");
const _bitMask = [1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536, 131072, 262144, 524288, 1048576, 2097152, 4194304, 8388608, 16777216, 33554432, 67108864, 134217728, 268435456, 536870912, 1073741824, 2147483648];

// print("const _clearMask = [${List<int>.generate(32, (i) => ~(1 << i)).join(", ")}];");
const _clearMask = [4294967294, 4294967293, 4294967291, 4294967287, 4294967279, 4294967263, 4294967231, 4294967167, 4294967039, 4294966783, 4294966271, 4294965247, 4294963199, 4294959103, 4294950911, 4294934527, 4294901759, 4294836223, 4294705151, 4294443007, 4293918719, 4292870143, 4290772991, 4286578687, 4278190079, 4261412863, 4227858431, 4160749567, 4026531839, 3758096383, 3221225471, 2147483647];

This appears to be a clear improvement (especially when it comes to AOT):

JIT
without baking: 8.3s~
with baking: 8s~
AOT
without baking: 9.4s~
with baking: 8.1s~

I din't bother with _cardinalityBitCounts because of #20.

@isoos what do you think?

[isoos]

I'm not sure how the change explains 300+ ms of runtime, but yeah, of course, we shall change it.

[modulovalue]

I'm not sure how the change explains 300+ ms of runtime

One of the masks is used by setBit and I suppose there's some inefficiency that adds up.

Note: CRoaring doesn't use tables for its setBit operation, but bit ops directly. That might be faster, I'm not sure, but with baked lists it's fast enough for my use case so I've not investigated that further.