[heap] Remove old_gen_exhausted_ state.

src/heap/heap.h

Index: src/heap/heap.h
diff --git a/src/heap/heap.h b/src/heap/heap.h
index 101c25fd180b3fc68ebb6f8b09e381070464c3d1..ed7421c6a4ec7fcf17fd6fc37fe57ce72ce337e2 100644
--- a/src/heap/heap.h
+++ b/src/heap/heap.h
@@ -2164,10 +2164,6 @@ class Heap {
   // generation and on every allocation in large object space.
   intptr_t old_generation_allocation_limit_;
 
-  // Indicates that an allocation has failed in the old generation since the
-  // last GC.
-  bool old_gen_exhausted_;
-
   // Indicates that inline bump-pointer allocation has been globally disabled
   // for all spaces. This is used to disable allocations in generated code.
   bool inline_allocation_disabled_;