Make window.scroll properties relative to the layout viewport.

Source/web/WebSettingsImpl.cpp

Index: Source/web/WebSettingsImpl.cpp
diff --git a/Source/web/WebSettingsImpl.cpp b/Source/web/WebSettingsImpl.cpp
index 098fd4f3f90fcec763683f90c10774ed991a7458..0d1f58affc36d264a60a751319d68946cc906413 100644
--- a/Source/web/WebSettingsImpl.cpp
+++ b/Source/web/WebSettingsImpl.cpp
@@ -190,6 +190,11 @@ void WebSettingsImpl::setInvertViewportScrollOrder(bool enabled)
     m_settings->setInvertViewportScrollOrder(enabled);
 }
 
+void WebSettingsImpl::setInertVisualViewport(bool enabled)
+{
+    m_settings->setInertVisualViewport(enabled);
+}
+
 void WebSettingsImpl::setDeviceScaleAdjustment(float deviceScaleAdjustment)
 {
     m_devToolsEmulator->setDeviceScaleAdjustment(deviceScaleAdjustment);