Remove use of MemMap for code allocation.

In preparation of moving to an executable code space.

Change-Id: I6cb6fec93c66005f8020d718fe3c1c5aa1c85356
diff --git a/src/heap.h b/src/heap.h
index 5168fe7..30133b7 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -21,9 +21,9 @@
 
 class Heap {
  public:
-  static const size_t kInitialSize = 16 * MB;
+  static const size_t kInitialSize = 64 * MB;  // TODO: lower to 4
 
-  static const size_t kMaximumSize = 64 * MB;
+  static const size_t kMaximumSize = 64 * MB;  // TODO: lower to 16
 
   typedef void (RootVisitor)(const Object* root, void* arg);