fix grid-rows with horizontal-gap > vertical-gap

[gavin-ts]

If there is a grid, with only grid-rows specified and not grid-columns, and if horizontal-gap is set to a positive value greater than vertical-gap, then the grid container may end up too short. This doesn't seem to happen with grid-columns.

grid: "" {
  grid-rows: 3
  horizontal-gap: 100
  vertical-gap: 0
  first
  second
  third
}

grid2: "" {
  grid-rows: 3
  horizontal-gap: 50
  vertical-gap: 0
  first
  second
  third
}

grid3: "" {
  grid-rows: 3
  horizontal-gap: 10
  vertical-gap: 0
  first
  second
  third
}

grid4: "" {
  grid-rows: 3
  horizontal-gap: 0
  vertical-gap: 0
  first
  second
  third
}

grid5: "" {
  grid-columns: 3
  horizontal-gap: 0
  vertical-gap: 100
  first
  second
  third
}

grid6: "" {
  grid-columns: 3
  horizontal-gap: 0
  vertical-gap: 10
  first
  second
  third
}