Add the eMetric_SubmenuDelay option.

r=kedl

widget/src/photon/nsLookAndFeel.cpp

@@ -168,9 +168,6 @@ NS_IMETHODIMP nsLookAndFeel::GetMetric(const nsMetricID aID, PRInt32 & aMetric)
 	case eMetric_CaretWidthTwips:
     aMetric = 20;
     break;
-  case eMetric_SubmenuDelay:
-    aMetric = 200;
-    break;
   default:
     aMetric = -1;
     res = NS_ERROR_FAILURE;