Replace GPOS and GDEF table diffs with otl-normalizer output?

[madig]

Fonts compiled with different compilers can have wildly different/reordered GDEF and GPOS tables. The table comparisons can produce megabytes of diffs that take too long to load and that no one is going to read. Would it be better to diff these two tables in particular with otl-normalizer and then display that diff output?

[simoncozens]

We should absolutely replace it with layout normalising code that we trust.