Bug 1465212 - Fix command line parameter checking in ExecInExplorer plugin. r=agashlin

Because of a silly logic error I made in bug 1494900, the optional command line
parameter support introduced there doesn't actually work at all; I reversed the
sense of the check for the NSIS stack being empty. This fixes that by just using
the check that the popstring function was already doing.

--HG--
extra : rebase_source : e63b70579810af5774e237c619b29fb71012ea8c
extra : source : 58a29f64dd06d4e66e6faf047e2356decc5904f4

other-licenses/nsis/Contrib/ExecInExplorer/ExecInExplorer.cpp

@@ -186,8 +186,7 @@ Exec(HWND, int, TCHAR *, stack_t **stacktop, void *)
   path[0] = L'\0';
   args[0] = L'\0';
   popstring(stacktop, path, MAX_PATH);
-  if (!stacktop || !*stacktop) {
-    popstring(stacktop, args, MAX_PATH);
+  if (popstring(stacktop, args, MAX_PATH) == 0) {
     // This stack item may not be for us, but we don't know yet.
     restoreArgString = true;
   }