From 43a42f108af6bcbd91f2672731c3047c26213af1 Mon Sep 17 00:00:00 2001
From: Simon Hausmann <simon.hausmann@digia.com>
Date: Mon, 22 Oct 2012 15:40:17 +0200
Subject: Imported WebKit commit 302e7806bff028bd1167a1ec7c86a1ee00ecfb49
 (http://svn.webkit.org/repository/webkit/trunk@132067)

New snapshot that fixes build without QtWidgets
---
 Source/WebCore/page/FrameView.cpp | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

(limited to 'Source/WebCore/page/FrameView.cpp')

diff --git a/Source/WebCore/page/FrameView.cpp b/Source/WebCore/page/FrameView.cpp
index 1be0c54c2..2d312a31a 100644
--- a/Source/WebCore/page/FrameView.cpp
+++ b/Source/WebCore/page/FrameView.cpp
@@ -2500,8 +2500,14 @@ void FrameView::performPostLayoutTasks()
     }
 
 #if USE(ACCELERATED_COMPOSITING)
-    if (TiledBacking* tiledBacking = this->tiledBacking())
-        tiledBacking->setTileCoverage(canHaveScrollbars() ? TiledBacking::CoverageForScrolling : TiledBacking::CoverageForVisibleArea);
+    if (TiledBacking* tiledBacking = this->tiledBacking()) {
+        if (page) {
+            if (ScrollingCoordinator* scrollingCoordinator = page->scrollingCoordinator()) {
+                bool shouldLimitTileCoverage = !canHaveScrollbars() || scrollingCoordinator->shouldUpdateScrollLayerPositionOnMainThread();
+                tiledBacking->setTileCoverage(shouldLimitTileCoverage ? TiledBacking::CoverageForVisibleArea : TiledBacking::CoverageForScrolling);
+            }
+        }
+    }
 #endif
 
     scrollToAnchor();
-- 
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