[cleanup] Remove stale TODOs related to RO_SPACE

The GetReadOnlyRoots will need to remain on HeapObject due to pointer
compression and the Isolate overload of HashSeed is convenient.

Change-Id: Id7fa8e57e3b8bfa6f50465c24da1fc5d0b4db0bd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2397889
Commit-Queue: Dan Elphick <delphick@chromium.org>
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Auto-Submit: Dan Elphick <delphick@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69729}

src/numbers/hash-seed-inl.h

@@ -19,7 +19,6 @@ namespace internal {
 class Isolate;
 class ReadOnlyRoots;
 
-// TODO(v8:7464): Remove the Isolate version of this.
 inline uint64_t HashSeed(Isolate* isolate);
 inline uint64_t HashSeed(ReadOnlyRoots roots);
 

src/objects/heap-object.h

@@ -62,9 +62,7 @@ class HeapObject : public Object {
   DECL_GETTER(synchronized_map_word, MapWord)
   inline void synchronized_set_map_word(MapWord map_word);
 
-  // TODO(v8:7464): Once RO_SPACE is shared between isolates, this method can be
-  // removed as ReadOnlyRoots will be accessible from a global variable. For now
-  // this method exists to help remove GetIsolate/GetHeap from HeapObject, in a
+  // This method exists to help remove GetIsolate/GetHeap from HeapObject, in a
   // way that doesn't require passing Isolate/Heap down huge call chains or to
   // places where it might not be safe to access it.
   inline ReadOnlyRoots GetReadOnlyRoots() const;