Add a ResourceConstraint for the embedder to specify that V8 is running on a memory constrained dev…

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index eb166ab68d2e53745f8659ae1c1648785488d215..6d5f00dc952bcc5802158d731f46c5e140930fd4 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -3763,11 +3763,16 @@ class V8EXPORT ResourceConstraints {
   uint32_t* stack_limit() const { return stack_limit_; }
   // Sets an address beyond which the VM's stack may not grow.
   void set_stack_limit(uint32_t* value) { stack_limit_ = value; }
+  bool is_memory_constrained() { return is_memory_constrained_; }
+  // If set to true, V8 will limit it's memory usage, at the potential cost of
+  // lower performance.
+  void set_memory_constrained(bool value) { is_memory_constrained_ = value; }
  private:
   int max_young_space_size_;
   int max_old_space_size_;
   int max_executable_size_;
   uint32_t* stack_limit_;
+  bool is_memory_constrained_;
 };