[sparkplug] Drop another TODO that was a design decision

Baseline scratch registers don't include the regular kScratchRegister
(for now at least) because the rest of the system doesn't use the
ScratchRegisterScope (yet).

Bug: v8:11429
Change-Id: I7a2f27a814e262e5b14bd30b2ae53d53e173bcc3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2697194Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Auto-Submit: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72771}

src/baseline/x64/baseline-compiler-x64-inl.h

@@ -17,8 +17,8 @@ namespace baseline {
 
 namespace detail {
 
-// TODO(v8:11429,verwaest): For now this avoids using kScratchRegister(==r10)
-// since the macro-assembler doesn't use this scope and will conflict.
+// Avoid using kScratchRegister(==r10) since the macro-assembler doesn't use
+// this scope and will conflict.
 static constexpr Register kScratchRegisters[] = {r8, r9, r11, r12, r14, r15};
 static constexpr int kNumScratchRegisters = arraysize(kScratchRegisters);