Delete fgMorphBlockOperand

[SingleAccretion]

No longer necessary as we don't need to compensate for invalid IR.

Diffs - a TP improvement, plus one small diff where we don't reduce OBJ(ADDR(LCL_VAR)) created by forward substitution, but it ends up being a bit better anyway.

[ghost]

Tagging subscribers to this area: @JulieLeeMSFT, @jakobbotsch
See info in area-owners.md if you want to be subscribed.

Issue Details

---

No longer necessary as we don't need to compensate for invalid IR.

A minor TP improvement is expected, with no code diffs.

Author:	SingleAccretion
Assignees:	-
Labels:	area-CodeGen-coreclr
Milestone:	-

[SingleAccretion]

Interesting OSX x64 (Libraries Test Run checked coreclr OSX x64 Debug) failure:

./RunTests.sh: line 168: 57924 Illegal instruction: 4  "$RUNTIME_PATH/dotnet" exec --runtimeconfig System.IO.FileSystem.Watcher.Tests.runtimeconfig.json --depsfile System.IO.FileSystem.Watcher.Tests.deps.json xunit.console.dll System.IO.FileSystem.Watcher.Tests.dll -xml testResults.xml -nologo -nocolor -notrait category=IgnoreForCI -notrait category=OuterLoop -notrait category=failing $RSP_FILE

Edit: machine was dci-mac-build-372.local.

Edit: I've run the CI a good number of times on this, and it did not reproduce. Will proceed with the change as-is for now.

[SingleAccretion]

@dotnet/jit-contrib

SPMI failures are due to missing Win-ARM64 collections.

[BruceForstall]

SPMI failures are due to missing Win-ARM64 collections.

This was due to an undetermined failure to upload files. A recollect is in progress (takes ~6 hours). There is a usual one scheduled on Sundays.