Don't set the limit that triggers the next GC higher than the max

src/heap.h

Index: src/heap.h
===================================================================
--- src/heap.h	(revision 9888)
+++ src/heap.h	(working copy)
@@ -1254,7 +1254,8 @@
         Max(old_gen_size + old_gen_size / divisor, kMinimumPromotionLimit);
     limit += new_space_.Capacity();
     limit *= old_gen_limit_factor_;
-    return limit;
+    intptr_t halfway_to_the_max = (old_gen_size + max_old_generation_size_) / 2;
+    return Min(limit, halfway_to_the_max);
   }
 
   intptr_t OldGenAllocationLimit(intptr_t old_gen_size) {
@@ -1263,7 +1264,8 @@
         Max(old_gen_size + old_gen_size / divisor, kMinimumAllocationLimit);
     limit += new_space_.Capacity();
     limit *= old_gen_limit_factor_;
-    return limit;
+    intptr_t halfway_to_the_max = (old_gen_size + max_old_generation_size_) / 2;
+    return Min(limit, halfway_to_the_max);
   }
 
   // Can be called when the embedding application is idle.