Increase old generation space significantly if we observe a high promotion rate.

src/heap.h

Index: src/heap.h
diff --git a/src/heap.h b/src/heap.h
index f1f9c36040fe9490ce62beb24d458560312737f3..b24b0b3608344ffba6177e42df6edf3c02f217e2 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -1585,6 +1585,11 @@ class Heap {
     intptr_t limit =
         Max(old_gen_size + old_gen_size / divisor, kMinimumPromotionLimit);
     limit += new_space_.Capacity();
+    // TODO(hpayer): Can be removed when when pretenuring is supported for all
+    // allocation sites.
+    if (IsHighSurvivalRate() && IsStableOrIncreasingSurvivalTrend()) {
+      limit *= 2;
+    }
     intptr_t halfway_to_the_max = (old_gen_size + max_old_generation_size_) / 2;
     return Min(limit, halfway_to_the_max);
   }
@@ -1595,6 +1600,11 @@ class Heap {
     intptr_t limit =
         Max(old_gen_size + old_gen_size / divisor, kMinimumAllocationLimit);
     limit += new_space_.Capacity();
+    // TODO(hpayer): Can be removed when when pretenuring is supported for all
+    // allocation sites.
+    if (IsHighSurvivalRate() && IsStableOrIncreasingSurvivalTrend()) {
+      limit *= 2;
+    }
     intptr_t halfway_to_the_max = (old_gen_size + max_old_generation_size_) / 2;
     return Min(limit, halfway_to_the_max);
   }