[heap] Fixes for heap testing

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index ad8d1466b92d8d6c43167914f395c6a8dc7394a2..fb5a4fb03cfae9a9c62dc44e788400dd8bbd27b6 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -5055,7 +5055,7 @@ bool Heap::ConfigureHeap(int max_semi_space_size, int max_old_space_size,
 
   if (FLAG_stress_compaction) {
     // This will cause more frequent GCs when stressing.
-    max_semi_space_size_ = Page::kPageSize;
+    max_semi_space_size_ = MB;
   }
 
   // The new space size must be a power of two to support single-bit testing