Avoid crashing when applying CSS to disconnected scrollbars

Assume the scrollbar has no scroll corner if it isn't attached to
any scrollable area.

Task-number: QTBUG-37679
Change-Id: Ib1bd2a4b1aa504885d52932b6c0fbd76daa356a5
Reviewed-by: Jocelyn Turcotte <jocelyn.turcotte@digia.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/Source/WebCore/css/SelectorChecker.cpp b/Source/WebCore/css/SelectorChecker.cpp
index dce313830..dd466bb92 100644
--- a/Source/WebCore/css/SelectorChecker.cpp
+++ b/Source/WebCore/css/SelectorChecker.cpp
@@ -880,7 +880,7 @@ bool SelectorChecker::checkScrollbarPseudoClass(const SelectorCheckingContext& c
             return false;
         }
     case CSSSelector::PseudoCornerPresent:
-        return scrollbar->scrollableArea()->isScrollCornerVisible();
+        return scrollbar->scrollableArea() ? scrollbar->scrollableArea()->isScrollCornerVisible() : false;
     default:
         return false;
     }