Merge pull request #20772 from mikedn/ir-cleanup

Some IR cleanup

diff --cc src/jit/codegen.h
Simple merge

diff --cc src/jit/codegenarmarch.cpp
Simple merge

diff --cc src/jit/codegencommon.cpp
Simple merge

diff --cc src/jit/codegenxarch.cpp
Simple merge

diff --cc src/jit/compiler.cpp
Simple merge

diff --cc src/jit/compiler.h
Simple merge

diff --cc src/jit/compiler.hpp
Simple merge

diff --cc src/jit/earlyprop.cpp
Simple merge

diff --cc src/jit/gentree.cpp
Simple merge

diff --cc src/jit/gentree.h
Simple merge

diff --cc src/jit/gtlist.h
Simple merge

diff --cc src/jit/gtstructs.h
Simple merge

diff --cc src/jit/importer.cpp
Simple merge

diff --cc src/jit/liveness.cpp
Simple merge

diff --cc src/jit/lower.cpp
Simple merge

diff --cc src/jit/morph.cpp
Simple merge

diff --cc src/jit/scopeinfo.cpp
Simple merge