[heap] Fix test failure with disabled map space

Fix failing tests with --no-use-map-space enabled.

Bug: v8:12578
Change-Id: I121b0d22cd69e76b6c5c02d1f83a166af0610b83
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3663343Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80717}

src/heap/paged-spaces.h

@@ -582,6 +582,7 @@ class OldGenerationMemoryChunkIterator {
   PageIterator old_iterator_;
   PageIterator code_iterator_;
   PageIterator map_iterator_;
+  const PageIterator map_iterator_end_;
   LargePageIterator lo_iterator_;
   LargePageIterator code_lo_iterator_;
 };

src/heap/spaces-inl.h

@@ -105,6 +105,8 @@ OldGenerationMemoryChunkIterator::OldGenerationMemoryChunkIterator(Heap* heap)
       code_iterator_(heap->code_space()->begin()),
       map_iterator_(heap->map_space() ? heap->map_space()->begin()
                                       : PageRange::iterator(nullptr)),
+      map_iterator_end_(heap->map_space() ? heap->map_space()->end()
+                                          : PageRange::iterator(nullptr)),
       lo_iterator_(heap->lo_space()->begin()),
       code_lo_iterator_(heap->code_lo_space()->begin()) {}
 
@@ -116,7 +118,7 @@ MemoryChunk* OldGenerationMemoryChunkIterator::next() {
       V8_FALLTHROUGH;
     }
     case kMapState: {
-      if (map_iterator_ != heap_->map_space()->end()) return *(map_iterator_++);
+      if (map_iterator_ != map_iterator_end_) return *(map_iterator_++);
       state_ = kCodeState;
       V8_FALLTHROUGH;
     }

test/unittests/api/isolate-unittest.cc

@@ -144,7 +144,11 @@ void CrashKeyCallback(v8::CrashKeyId id, const std::string& value) {
 }  // namespace
 TEST_F(IsolateTest, SetAddCrashKeyCallback) {
   isolate()->SetAddCrashKeyCallback(CrashKeyCallback);
-  EXPECT_EQ(crash_keys.size(), 6u);
+
+  internal::Isolate* i_isolate =
+      reinterpret_cast<internal::Isolate*>(isolate());
+  const bool has_map_space = i_isolate->heap()->map_space() != nullptr;
+  EXPECT_EQ(crash_keys.size(), has_map_space ? 6u : 5u);
 }
 
 }  // namespace v8