scrrun/dictionary: Add support for hashing VT_NULL keys.

dlls/scrrun/dictionary.c

@@ -910,6 +910,7 @@ static HRESULT WINAPI dictionary_get_HashVal(IDictionary *iface, VARIANT *key, V
     case VT_R8:
         return get_flt_hash(V_VT(key) & VT_BYREF ? *V_R8REF(key) : V_R8(key), &V_I4(hash));
     case VT_EMPTY:
+    case VT_NULL:
         V_I4(hash) = 0;
         return S_OK;
     case VT_INT:

dlls/scrrun/tests/dictionary.c

@@ -753,6 +753,14 @@ if (0) { /* crashes on native */
     ok(V_VT(&hash) == VT_I4, "Unexpected hash type %d.\n", V_VT(&hash));
     ok(V_I4(&hash) == 0, "Unexpected hash value %ld.\n", V_I4(&hash));
 
+    V_VT(&key) = VT_NULL;
+    V_I4(&key) = 1234;
+    V_I4(&hash) = 5678;
+    hr = IDictionary_get_HashVal(dict, &key, &hash);
+    ok(hr == S_OK, "Unexpected hr %#lx.\n", hr);
+    ok(V_VT(&hash) == VT_I4, "Unexpected hash type %d.\n", V_VT(&hash));
+    ok(V_I4(&hash) == 0, "Unexpected hash value %ld.\n", V_I4(&hash));
+
     IDictionary_Release(dict);
 }