Revert "JIT: Account for mixed-enregistered locals when zeroing witho…

…ut block-init (dotnet#104593)"

This reverts commit d586986.

src/coreclr/jit/codegencommon.cpp

@@ -4055,15 +4055,9 @@ void CodeGen::genZeroInitFrame(int untrLclHi, int untrLclLo, regNumber initReg,
  continue;
  }
 
- // Locals that are (only) in registers to begin with do not need
- // their stack home zeroed. Their register will be zeroed later in
- // the prolog.
- if (varDsc->lvIsInReg() && !varDsc->lvLiveInOutOfHndlr)
- {
- continue;
- }
-
- noway_assert(varDsc->lvOnFrame);
+ // TODO-Review: I'm not sure that we're correctly handling the mustInit case for
+ // partially-enregistered vars in the case where we don't use a block init.
+ noway_assert(varDsc->lvIsInReg() || varDsc->lvOnFrame);
 
  // lvMustInit can only be set for GC types or TYP_STRUCT types
  // or when compInitMem is true
@@ -4072,6 +4066,11 @@ void CodeGen::genZeroInitFrame(int untrLclHi, int untrLclLo, regNumber initReg,
  noway_assert(varTypeIsGC(varDsc->TypeGet()) || (varDsc->TypeGet() == TYP_STRUCT) ||
  compiler->info.compInitMem || compiler->opts.compDbgCode);
 
+ if (!varDsc->lvOnFrame)
+ {
+ continue;
+ }
+
  if ((varDsc->TypeGet() == TYP_STRUCT) && !compiler->info.compInitMem &&
  (varDsc->lvExactSize() >= TARGET_POINTER_SIZE))
  {