[liftoff][arm64] Remove outdated comment

The comment is a left-over of the state before
https://crrev.com/c/3055302. It should have been removed as part of that
CL.

R=ahaas@chromium.org

Bug: v8:12017
Change-Id: Ic5234b230b3eda30e9a4a346e8c3b83c813a5dbf
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3059078Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75989}

src/wasm/baseline/arm64/liftoff-assembler-arm64.h

@@ -359,8 +359,6 @@ void LiftoffAssembler::PatchPrepareStackFrame(
     B(hs /* higher or same */, &continuation);
   }
 
-  // The instance was not written to the frame yet, but the slot was already
-  // reserved in {EnterFrame}. The runtime call expects it, thus spill it now.
   Call(wasm::WasmCode::kWasmStackOverflow, RelocInfo::WASM_STUB_CALL);
   // The call will not return; just define an empty safepoint.
   safepoint_table_builder->DefineSafepoint(this);