fix firefox test

lib/ScriptInterpreter.js

@@ -704,7 +704,6 @@ ScriptInterpreter.prototype.eval = function eval(script, tx, inIndex, hashType,
             var success = true,
               isig = 0,
               ikey = 0;
-            checkMultiSigStep.call(this);
 
             function checkMultiSigStep() {
               if (success && sigsCount > 0) {
@@ -742,6 +741,7 @@ ScriptInterpreter.prototype.eval = function eval(script, tx, inIndex, hashType,
                 executeStep.call(this, cb);
               }
             };
+            checkMultiSigStep.call(this);
 
             // Note that for asynchronous opcodes we have to return here to prevent
             // the next opcode from being executed.