anchor.diff:    Expect.identical(-0.0, box[0]);
     box = [-1];
     Expect.identical(-1.0, box[0]);
  -  box = [9223372036854776000];
  -  Expect.identical(9223372036854776000.0, box[0]);
  -  box = [18446744073709552000];
  -  Expect.identical(18446744073709552000.0, box[0]);
  +  box = [9223372036854775808];
  +  Expect.identical(9223372036854775808.0, box[0]);
  +  box = [18446744073709551616];
  +  Expect.identical(18446744073709551616.0, box[0]);
     box = [0x02];
     Expect.identical(2.0, box[0]);
     box = [-0x02];
  
positive.code:   Expect.identical(-0.0, map.keys.first);
    map = <double, Null>{-1: null};
    Expect.identical(-1.0, map.keys.first);
    map = <double, Null>{9223372036854776000: null};
    Expect.identical(9223372036854776000.0, map.keys.first);
    map = <double, Null>{18446744073709552000: null};
    Expect.identical(18446744073709552000.0, map.keys.first);
    map = <double, Null>{0x02: null};
    Expect.identical(2.0, map.keys.first);
    map = <double, Null>{-0x02: null};
  
negative.code:   v4 = -1
      ..toString();
    Expect.identical(-1.0, v4);
    v5 = 9223372036854775808..toString();
    Expect.identical(9223372036854775808.0, v5);
    v6 = 18446744073709551616..toString();
    Expect.identical(18446744073709551616.0, v6);
    v7 = 0x02..toString(); // Hex literal.
    Expect.identical(2.0, v7);
    v8 = -0x02
  