Add allocation and garbage collection infrastructure.

Change-Id: I4b04cdfdf18afb75a7b0df87b509e8156b4a932b
diff --git a/src/runtime.h b/src/runtime.h
index 9245f19..cbccccb 100644
--- a/src/runtime.h
+++ b/src/runtime.h
@@ -39,15 +39,13 @@
  private:
   static void PlatformAbort(const char*, int);
 
-  Runtime() : class_linker_(NULL), heap_(NULL), thread_list_(NULL) {}
+  Runtime() : class_linker_(NULL), thread_list_(NULL) {}
 
   // Initializes a new uninitialized runtime.
   bool Init();
 
   ClassLinker* class_linker_;
 
-  Heap* heap_;
-
   ThreadList* thread_list_;
 
   DISALLOW_COPY_AND_ASSIGN(Runtime);