Put store buffer verification behind a flag.

src/store-buffer.cc

Index: src/store-buffer.cc
diff --git a/src/store-buffer.cc b/src/store-buffer.cc
index ab810e40060e867c5a0960fc60152b3696baa4b3..c67d147fb4d06cef927f873180b211027e828d22 100644
--- a/src/store-buffer.cc
+++ b/src/store-buffer.cc
@@ -390,11 +390,13 @@ void StoreBuffer::VerifyPointers(LargeObjectSpace* space) {
 
 void StoreBuffer::Verify() {
 #ifdef DEBUG
-  VerifyPointers(heap_->old_pointer_space(),
-                 &StoreBuffer::FindPointersToNewSpaceInRegion);
-  VerifyPointers(heap_->map_space(),
-                 &StoreBuffer::FindPointersToNewSpaceInMapsRegion);
-  VerifyPointers(heap_->lo_space());
+  if (FLAG_enable_slow_asserts || FLAG_verify_heap) {
+    VerifyPointers(heap_->old_pointer_space(),
+                   &StoreBuffer::FindPointersToNewSpaceInRegion);
+    VerifyPointers(heap_->map_space(),
+                   &StoreBuffer::FindPointersToNewSpaceInMapsRegion);
+    VerifyPointers(heap_->lo_space());
+  }
 #endif
 }