Add missing if (FLAG_verify_heap) checks around heap verification

src/heap-snapshot-generator.cc

Index: src/heap-snapshot-generator.cc
diff --git a/src/heap-snapshot-generator.cc b/src/heap-snapshot-generator.cc
index dec42a8b5fdd1812d488ade889d6f068db530f9f..ec1f645cadb1048bd1f62d615feddb88534b755a 100644
--- a/src/heap-snapshot-generator.cc
+++ b/src/heap-snapshot-generator.cc
@@ -2551,13 +2551,17 @@ bool HeapSnapshotGenerator::GenerateSnapshot() {
 
 #ifdef VERIFY_HEAP
   Heap* debug_heap = heap_;
-  debug_heap->Verify();
+  if (FLAG_verify_heap) {
+    debug_heap->Verify();
+  }
 #endif
 
   SetProgressTotal(2);  // 2 passes.
 
 #ifdef VERIFY_HEAP
-  debug_heap->Verify();
+  if (FLAG_verify_heap) {
+    debug_heap->Verify();
+  }
 #endif
 
   snapshot_->AddSyntheticRootEntries();