Remove re-entrancy check for another PR.

Author: juj

src/preamble.js

@@ -188,19 +188,12 @@ function preMain() {
 #endif
 
 #if EXIT_RUNTIME
-
-#if ASSERTIONS
-var runtimeExiting = false;
-#endif
-
 function exitRuntime() {
 #if RUNTIME_DEBUG
   dbg('exitRuntime');
 #endif
 #if ASSERTIONS
   assert(!runtimeExited);
-  assert(!runtimeExiting, 'Re-entrant call to exitRuntime()! This can happen if an atexit() registered callback throws an exception.');
-  runtimeExiting = true;
 #endif
 #if ASYNCIFY == 1 && ASSERTIONS
   // ASYNCIFY cannot be used once the runtime starts shutting down.