[WebAssembly] Fix a bug when mixing TRY/LOOP markers

[WebAssembly] Fix a bug when mixing TRY/LOOP markers

Summary:
When TRY and LOOP markers are in the same BB and END_TRY and END_LOOP
markers are in the same BB, END_TRY should be _before_ END_LOOP, because
LOOP is always before TRY if they are in the same BB. (TRY is placed in
the latest possible position, whereas LOOP is in the earliest possible
position.)

Reviewers: dschuff

Subscribers: sunfish, sbc100, jgravelle-google, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59751

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@357008 91177308-0d34-0410-b5e6-96231b3b80d8