mshtml: Properly handle OOM errors in omnavigator.c (coverity).

dlls/mshtml/htmlwindow.c

@@ -803,7 +803,7 @@ static HRESULT WINAPI HTMLWindow2_get_navigator(IHTMLWindow2 *iface, IOmNavigato
     TRACE("(%p)->(%p)\n", This, p);
 
     *p = OmNavigator_Create();
-    return S_OK;
+    return *p ? S_OK : E_OUTOFMEMORY;
 }
 
 static HRESULT WINAPI HTMLWindow2_put_name(IHTMLWindow2 *iface, BSTR v)

dlls/mshtml/omnavigator.c

@@ -941,6 +941,9 @@ IOmNavigator *OmNavigator_Create(void)
     OmNavigator *ret;
 
     ret = heap_alloc_zero(sizeof(*ret));
+    if(!ret)
+        return NULL;
+
     ret->IOmNavigator_iface.lpVtbl = &OmNavigatorVtbl;
     ret->ref = 1;