[heap] Move VerifySmisVisitor into heap-verifier.cc

This class is only used for heap verification and doesn't need to be
public.

Bug: v8:11708
Change-Id: I9d1750a6f701ed0d9a106f8d93ab3ff82bbf4f3b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3862208Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82814}

src/heap/heap-verifier.cc

@@ -29,6 +29,17 @@
 namespace v8 {
 namespace internal {
 
+// Verify that all objects are Smis.
+class VerifySmisVisitor final : public RootVisitor {
+ public:
+  void VisitRootPointers(Root root, const char* description,
+                         FullObjectSlot start, FullObjectSlot end) override {
+    for (FullObjectSlot current = start; current < end; ++current) {
+      CHECK((*current).IsSmi());
+    }
+  }
+};
+
 class HeapVerification final {
  public:
   explicit HeapVerification(Heap* heap) : heap_(heap) {}

src/heap/heap.cc

@@ -6729,14 +6729,6 @@ void VerifyPointersVisitor::VisitEmbeddedPointer(Code host, RelocInfo* rinfo) {
   VerifyHeapObjectImpl(rinfo->target_object(cage_base()));
 }
 
-void VerifySmisVisitor::VisitRootPointers(Root root, const char* description,
-                                          FullObjectSlot start,
-                                          FullObjectSlot end) {
-  for (FullObjectSlot current = start; current < end; ++current) {
-    CHECK((*current).IsSmi());
-  }
-}
-
 bool Heap::AllowedToBeMigrated(Map map, HeapObject obj, AllocationSpace dst) {
   // Object migration is governed by the following rules:
   //

src/heap/heap.h

@@ -2714,13 +2714,6 @@ class VerifyPointersVisitor : public ObjectVisitorWithCageBases,
   Heap* heap_;
 };
 
-// Verify that all objects are Smis.
-class VerifySmisVisitor : public RootVisitor {
- public:
-  void VisitRootPointers(Root root, const char* description,
-                         FullObjectSlot start, FullObjectSlot end) override;
-};
-
 // Space iterator for iterating over all the paged spaces of the heap: Map
 // space, old space and code space. Returns each space in turn, and null when it
 // is done.