Lose/restore WebGL contexts if multisampling blackist status changes at runtime.

Source/core/page/Settings.cpp

Index: Source/core/page/Settings.cpp
diff --git a/Source/core/page/Settings.cpp b/Source/core/page/Settings.cpp
index e81ec667ec3c3894a65f7040281ac72db5b4d84f..f47b12f3df3d421eca3938d1f7b9fc5b59583291 100644
--- a/Source/core/page/Settings.cpp
+++ b/Source/core/page/Settings.cpp
@@ -381,4 +381,18 @@ bool Settings::usesOverlayScrollbars()
     return gUsesOverlayScrollbars;
 }
 
+void Settings::setOpenGLMultisamplingEnabled(bool flag)
+{
+    if (m_openGLMultisamplingEnabled == flag)
+        return;
+
+    m_openGLMultisamplingEnabled = flag;
+    m_page->multisamplingChanged();
+}
+
+bool Settings::openGLMultisamplingEnabled()
+{
+    return m_openGLMultisamplingEnabled;
+}
+
 } // namespace WebCore