Mis-Shaping Chakma Maayyaa U+11134

[brawer]

https://github.com/googlei18n/noto-fonts/issues/1263 (reported by @Bivuti) sounds like an Harfbuzz issue; see there for details.

[punchcutter]

Yes, U+11134 needs a USE override to be Gemination_Mark instead of Pure_Killer. That will give it use category CMAbv which in USE cluster validation is allowed before the other marks. The other thing we should do is remove the decompose_use special-casing for Chakma split-vowels. At the same time we need to make sure we update the other USE overrides as mentioned here: #539, but @dscorbett makes a good point in #982 that we shouldn't necessarly override everything to VBlw.