WebAssembly: simply assert on SNaN and NaNs with payloads

Summary: convertToHexString doesn't represent them correctly at this point in time. This is a follow-up to sunfish's suggestion in D11914.

Subscribers: llvm-commits, sunfish, jfb

Differential Revision: http://reviews.llvm.org/D11925

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@244551 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed