Reland of "[heap] Switch to 500k pages"

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index cd67eca479316a5d9d2900dd2140667bc3a3e528..10d6deeeb0e6d273eaf1c72094523c52f5a8c9f3 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -4802,6 +4802,7 @@ class FreeSpace: public HeapObject {
   // Size is smi tagged when it is stored.
   static const int kSizeOffset = HeapObject::kHeaderSize;
   static const int kNextOffset = POINTER_SIZE_ALIGN(kSizeOffset + kPointerSize);
+  static const int kSize = kNextOffset + kPointerSize;
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(FreeSpace);
@@ -10563,12 +10564,12 @@ 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
+  // 400 * KB 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) /
+      (400 * KB - FixedArray::kHeaderSize - kSize - AllocationMemento::kSize) /
       kPointerSize;
 
  private: