re-landing 398898 after it was backed out in an attempt to find a perf regression. patch by Stan Shebs. r=josh sr=roc

widget/src/cocoa/nsClipboard.mm

@@ -93,7 +93,10 @@ nsClipboard::SetNativeClipboardData(PRInt32 aWhichClipboard)
   for (unsigned int i = 0; i < outputCount; i++) {
     NSString* currentKey = [outputKeys objectAtIndex:i];
     id currentValue = [pasteboardOutputDict valueForKey:currentKey];
-    if (currentKey == NSStringPboardType)
+    if (currentKey == NSStringPboardType ||
+        currentKey == kCorePboardType_url ||
+        currentKey == kCorePboardType_urld ||
+        currentKey == kCorePboardType_urln)
       [generalPBoard setString:currentValue forType:currentKey];
     else
       [generalPBoard setData:currentValue forType:currentKey];