[instruction-scheduler] Do not re-order nodes around kArchDebugBreak.

When debugging CSA builtins, it's useful to place a 'DebugBreak();' in the
code. However, the instruction scheduler re-orders instructions around it which
can be a little frustrating.

Change-Id: Ic4288bbc24e78987c7cbf3616e80cf5915f474c4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1916602Reviewed-by: Georg Neis <neis@chromium.org>
Commit-Queue: Pierre Langlois <pierre.langlois@arm.com>
Cr-Commit-Position: refs/heads/master@{#64963}

src/compiler/backend/instruction-scheduler.cc

@@ -311,9 +311,11 @@ int InstructionScheduler::GetInstructionFlags(const Instruction* instr) const {
     case kArchTailCallAddress:
     case kArchTailCallWasm:
     case kArchAbortCSAAssert:
-    case kArchDebugBreak:
       return kHasSideEffect;
 
+    case kArchDebugBreak:
+      return kIsBarrier;
+
     case kArchSaveCallerRegisters:
     case kArchRestoreCallerRegisters:
       return kIsBarrier;