Rename debug to disable_assertions in toolhelper and callsites

Change-Id: Iffa181c0b09ab4cf989772b43e0bed257ec21cfd
diff --git a/tools/r8.py b/tools/r8.py
index a2f54ce..a6bf42e 100755
--- a/tools/r8.py
+++ b/tools/r8.py
@@ -63,7 +63,7 @@
     return toolhelper.run('r8',
                           r8_args,
                           build=not options.no_build,
-                          debug=not options.disable_assertions,
+                          disable_assertions=options.disable_assertions,
                           debug_agent=options.debug_agent,
                           jar=utils.find_r8_jar_from_options(options),
                           main='com.android.tools.r8.R8',