SCUMM: 2nd try to fix dungeon door timing

Shorten the timer delay does not work as escaping with a second kid is not possible too. Instead decrease engine speed during script execution.

engines/scumm/script_v2.cpp

@@ -1433,17 +1433,6 @@ void ScummEngine_v2::o2_delay() {
 	delay |= fetchScriptByte() << 16;
 	delay = 0xFFFFFF - delay;
 
-	// WORKAROUND: walking speed in the original v0/v1 interpreter 
-	// is sometimes slower (e.g. during scrolling) than in ScummVM.
-	// Hence, the delay for the door-closing action in the dungeon 
-	// is to long, so a single kid is able to escape -> shorten delay.
-	int script = vm.slot[_currentScript].number;
-	if ((_game.version == 0 && script == 132) || 
-		(_game.version == 1 && script == 137)) {
-		if (delay == 180)
-			delay = 120;
-	}
-
 	vm.slot[_currentScript].delay = delay;
 	vm.slot[_currentScript].status = ssPaused;
 	o5_breakHere();

engines/scumm/scumm.cpp

@@ -1964,6 +1964,14 @@ Common::Error ScummEngine::go() {
 		if (delta < 1)	// Ensure we don't get into an endless loop
 			delta = 1;  // by not decreasing sleepers.
 
+		// WORKAROUND: walking speed in the original v0/v1 interpreter 
+		// is sometimes slower (e.g. during scrolling) than in ScummVM.
+		// This is important for the door-closing action in the dungeon,
+		// otherwise (delta < 6) a single kid is able to escape. 
+		if ((_game.version == 0 && isScriptRunning(132)) || 
+			(_game.version == 1 && isScriptRunning(137)))
+			delta = 6;
+
 		// Wait...
 		waitForTimer(delta * 1000 / 60 - diff);