Make header include guards great again

runtime/vm/heap.h

Index: runtime/vm/heap.h
diff --git a/runtime/vm/heap.h b/runtime/vm/heap.h
index deae0a0bfed37e580b6ab50d0aa6a20b325667f0..30210bc54c86fe048b189b6a7ca0c4ce53c5e0b5 100644
--- a/runtime/vm/heap.h
+++ b/runtime/vm/heap.h
@@ -2,8 +2,8 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-#ifndef VM_HEAP_H_
-#define VM_HEAP_H_
+#ifndef RUNTIME_VM_HEAP_H_
+#define RUNTIME_VM_HEAP_H_
 
 #include "platform/assert.h"
 #include "vm/allocation.h"
@@ -396,4 +396,4 @@ class WritableVMIsolateScope : StackResource {
 
 }  // namespace dart
 
-#endif  // VM_HEAP_H_
+#endif  // RUNTIME_VM_HEAP_H_