OptimizeTempVarsPass doesn't need to run on child scopes upfront

* Let this run on child scopes on demand so that it follows the
  new lifecycle.

* Eliminates crashers when run on closures from parent scopes.

core/src/main/java/org/jruby/ir/passes/OptimizeTempVarsPass.java

@@ -18,10 +18,6 @@ public String getLabel() {
 
     @Override
     public Object execute(IRScope s, Object... data) {
-        for (IRClosure c: s.getClosures()) {
-            run(c, false, true);
-        }
-
         optimizeTmpVars(s);
 
         return null;