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

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 320531cfd588aa61ebd344477be4202cd3cd95fb..e109fa68d72db141fbd62564aef50d13072f8e19 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -10584,12 +10584,13 @@ class JSArray: public JSObject {
   static const int kLengthOffset = JSObject::kHeaderSize;
   static const int kSize = kLengthOffset + kPointerSize;
 
-  // 600 * KB is the Page::kMaxRegularHeapObjectSize defined in spaces.h which
-  // we do not want to include in objects.h
+  // (512 * KB - 384) is the Page::kMaxRegularHeapObjectSize defined in spaces.h
+  // which we do not want to include in objects.h
   // Note that Page::kMaxRegularHeapObjectSize has to be in sync with
   // kInitialMaxFastElementArray which is checked in a DCHECK in heap.cc.
   static const int kInitialMaxFastElementArray =
-      (600 * KB - FixedArray::kHeaderSize - kSize - AllocationMemento::kSize) /
+      (512 * KB - 384 - FixedArray::kHeaderSize - kSize -
+       AllocationMemento::kSize) /
       kPointerSize;
 
  private: