[maglev] Set properties as constexpr

Fixes https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Linux64%20-%20gcov%20coverage/29098/overview
and https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Linux64%20gcc%20-%20debug%20builder/1389/overview

Bug: v8:7700
Change-Id: I90717b9644b75cef28656893d37aa57e5f03e2fe
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3599478
Auto-Submit: Victor Gomes <victorgomes@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Commit-Queue: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80109}

src/maglev/maglev-ir.h

@@ -453,7 +453,7 @@ class NodeBase : public ZoneObject {
       OpProperties::Pure() | OpProperties::TaggedValue();
 
   constexpr Opcode opcode() const { return OpcodeField::decode(bit_field_); }
-  OpProperties properties() const {
+  constexpr OpProperties properties() const {
     return OpPropertiesField::decode(bit_field_);
   }