Check matadata and private blocks offsets & length
Check matadata and private blocks offsets & length

So that we can reject fonts with extraneous data between blocks, as the
spec says we should reject says we should reject such fonts.

bxchusun/le-huong-van,bxchusun/le-huong-van,google/woff2,anthrotype/woff2,bxchusun/le-huong-van,rsheeter/woff2,bxchusun/le-huong-van,khaledhosny/woff2