height: 100% changes a calculation based on sibling's intrinsic vs. explicit height

[matthew-dean]

I couldn't tell if this was related to other bugs, although I think there are similar % calculations that may be related.

Basically, I discovered that, within a grid, a "cell's" child's height calculation for 100% changes if other content within that cell has its height set explicitly vs. intrinsically. In other words, the grid item is the exact same visible height, but if content has an explicit height, then sibling element's 100% calculation will act differently vs. the content having an intrinsic height of the same value.

Codepen: https://codepen.io/matthewdean/pen/LrZxjX
Bug filed: https://bugs.chromium.org/p/chromium/issues/detail?id=849945