Add sanity checks about memory-related numbers.

Change-Id: Ia85130d7dda61e94405dbf3057b4de35a6994ab5
diff --git a/tools/internal_test.py b/tools/internal_test.py
index 9654b4b..d3ede75 100755
--- a/tools/internal_test.py
+++ b/tools/internal_test.py
@@ -90,6 +90,8 @@
 ]
 
 def find_min_xmx_command(record):
+  assert record['find-xmx-min'] < record['find-xmx-max']
+  assert record['find-xmx-range'] < record['find-xmx-max'] - record['find-xmx-min']
   return [
       'tools/run_on_app.py',
       '--compiler=r8',