[heap] Change LO space limit to 512k - page header

src/heap/spaces.h

Index: src/heap/spaces.h
diff --git a/src/heap/spaces.h b/src/heap/spaces.h
index 780c148b3ccd6caa3001f19970e926cdced0eaac..d024c4b6a3000e700e7bda19313c92024c764a6c 100644
--- a/src/heap/spaces.h
+++ b/src/heap/spaces.h
@@ -716,7 +716,7 @@ class Page : public MemoryChunk {
   // account.
   // TODO(hpayer): This limit should be way smaller but we currently have
   // short living objects >256K.
-  static const int kMaxRegularHeapObjectSize = 600 * KB;
+  static const int kMaxRegularHeapObjectSize = 512 * KB - Page::kHeaderSize;
 
   static inline Page* ConvertNewToOld(Page* old_page, PagedSpace* new_owner);