Update the interpolation-operators-precedence spec

[xzyfer]

This updates the interpolation-operators-precedence to match the
behaviour expected by sass/sass#2160.

This will need a sanity check by @nex3

This spec were generated with sass/sass#2163 applied to sass#stable

[xzyfer]

LibSass will currently fail this spec

[mgreter]

FWIW I lately used this test to try to get libsass in line with ruby sass:

tst {
  a01: (#{a} - 5% / 2);
  a11: (#{a} + 5% / 2);
  a02: (#{a} -5% / 2);
  a12: (#{a} +5% / 2);
  a03: (#{a}-5% / 2);
  a13: (#{a}+5% / 2);
  b01: (a - 5% / 2);
  b11: (a + 5% / 2);
  b02: (a -5% / 2);
  b12: (a +5% / 2);
  b03: (a-5px / 2);
  b13: (a+5px / 2);
}

tst {
  a01: (#{a} - 5.0% / 2);
  a11: (#{a} + 5.0% / 2);
  a02: (#{a} -5.0% / 2);
  a12: (#{a} +5.0% / 2);
  a03: (#{a}-5.0% / 2);
  a13: (#{a}+5.0% / 2);
  b01: (a - 5.0% / 2);
  b11: (a + 5.0% / 2);
  b02: (a -5.0% / 2);
  b12: (a +5.0% / 2);
  b03: (a-5.0% / 2);
  b13: (a+5.0% / 2);
}

tst {
  test-01: a #{5.0px / 2};
  test-02: a #{+5.0px / 2};
  test-03: a #{-5.0px / 2};
  test-04: #{+5.0px / 2};
  test-04: #{-5.0px / 2};
  test-04: #{5.0px / 2};
  test-04: #{a} -5.0px / 2;
}

tst {
  test-05: (a 5.0px / 2);
  test-06: (#{a} 9.0px / 2);
  test-0A: (5.0px / 2 a);
  test-07: (9.0px / 2 #{a});
  test-08: (9.0px / 2 #{a} 9.0px / 2);
  test-09: (a 5.0px / 2 #{a} 9.0px / 2);
  test-10: (a, 5.0px / 2 #{a} 5.0px / 2);

  test-11: (9.0px / 2 #{a} 9.0px / 2 #{a});
  test-12: (9.0px / 2 #{a} #{a} 9.0px / 2);
  test-13: (#{a} 9.0px / 2 #{a} 9.0px / 2);
  test-14: (#{a} 5.0px / 2 5.0px / 2 #{a});

  test-15: a 5.0px / 2;
  test-16: #{a} 9.0px / 2;
  test-17: 9.0px / 2 #{a};
  test-18: 9.0px / 2 #{a} 9.0px / 2;
  test-19: a 5.0px / 2 #{a} -9.0px / 2;
  test-20: a, 5.0px / 2 #{a} 5.0px / 2;

  test-21: 9.0px / 2 #{a} 9.0px / 2 #{a};
  test-22: 9.0px / 2 #{a} #{a} 9.0px / 2;
  test-23: #{a} 9.0px / 2 #{a} 9.0px / 2;
  test-24: #{a} 5.0px / 2 5.0px / 2 #{a};
}

ruby sass 3.4.22

tst {
  a01: a - 2.5%;
  a11: a + 2.5%;
  a02: a -2.5%;
  a12: a +2.5%;
  a03: a-2.5%;
  a13: a+2.5%;
  b01: a-2.5%;
  b11: a2.5%;
  b02: a -5%/2;
  b12: a2.5%;
  b03: a-5px/2;
  b13: a2.5px;
}

tst {
  a01: a - 2.5%;
  a11: a + 2.5%;
  a02: a -2.5%;
  a12: a +2.5%;
  a03: a-2.5%;
  a13: a+2.5%;
  b01: a-2.5%;
  b11: a2.5%;
  b02: a -5%/2;
  b12: a2.5%;
  b03: a-5 0%/2;
  b13: a2.5%;
}

tst {
  test-01: a 5px/2;
  test-02: a 5px/2;
  test-03: a -2.5px;
  test-04: 5px/2;
  test-04: -2.5px;
  test-04: 5px/2;
  test-04: a -5px/2;
}

tst {
  test-05: a 5px/2;
  test-06: a 4.5px;
  test-0A: 5px/2 a;
  test-07: 4.5px a;
  test-08: 4.5px a 4.5px;
  test-09: a 5px/2 a 4.5px;
  test-10: a, 5px/2 a 5px/2;
  test-11: 4.5px a 4.5px a;
  test-12: 4.5px a a 4.5px;
  test-13: a 4.5px a 4.5px;
  test-14: a 5px/2 5px/2 a;
  test-15: a 5.0px / 2;
  test-16: a 9px/2;
  test-17: 9px/2 a;
  test-18: 9px/2 a 9px/2;
  test-19: a 5px/2 a -9px/2;
  test-20: a, 5px/2 a 5px/2;
  test-21: 9px/2 a 9px/2 a;
  test-22: 9px/2 a a 9px/2;
  test-23: a 9px/2 a 9px/2;
  test-24: a 5px/2 5px/2 a;
}

[nex3]

I believe these specs have been updated elsewhere.