WebKit: Turn off accelerated compositing.

Compositing depends on Graphics View and/or GL-based texture mapper.
Since we don't plan to support either of them, at least for the near
future, we might as well disable compositing.

http://code.google.com/p/phantomjs/issues/detail?id=414

src/qt/src/3rdparty/webkit/Source/JavaScriptCore/wtf/Platform.h

@@ -1158,7 +1158,7 @@
 #endif
 
 /* Accelerated compositing */
-#if PLATFORM(MAC) || PLATFORM(IOS) || PLATFORM(QT) || (PLATFORM(WIN) && !OS(WINCE) &&!defined(WIN_CAIRO))
+#if PLATFORM(MAC) || PLATFORM(IOS) || (PLATFORM(WIN) && !OS(WINCE) &&!defined(WIN_CAIRO))
 #define WTF_USE_ACCELERATED_COMPOSITING 1
 #endif
 

src/qt/src/3rdparty/webkit/Source/WebCore/plugins/qt/PluginViewQt.cpp

@@ -182,6 +182,7 @@ void PluginView::updatePluginWidget()
         || (QWebPagePrivate::drtRun && platformPluginWidget() && (m_windowRect != oldWindowRect || m_clipRect != oldClipRect)))
         setNPWindowIfNeeded();
 
+#if USE(ACCELERATED_COMPOSITING)
     if (!m_platformLayer) {
         // Make sure we get repainted afterwards. This is necessary for downward
         // scrolling to move the plugin widget properly.
@@ -190,6 +191,7 @@ void PluginView::updatePluginWidget()
         // to the frame again) before passing it to FrameView.
         invalidate();
     }
+#endif
 }
 
 void PluginView::setFocus(bool focused)

src/qt/src/3rdparty/webkit/Source/WebKit/qt/Api/qwebview.cpp

@@ -22,6 +22,9 @@
 #include "config.h"
 #include "qwebview.h"
 
+#include <wtf/OwnPtr.h>
+#include <wtf/PassOwnPtr.h>
+
 #include "Page.h"
 #include "QWebPageClient.h"
 #include "Settings.h"

src/qt/src/3rdparty/webkit/Source/WebKit/qt/WebCoreSupport/ChromeClientQt.cpp

@@ -133,7 +133,11 @@ bool ChromeClientQt::allowsAcceleratedCompositing() const
 {
     if (!platformPageClient())
         return false;
+#if USE(ACCELERATED_COMPOSITING)
     return platformPageClient()->allowsAcceleratedCompositing();
+#else
+    return false;
+#endif
 }
 
 FloatRect ChromeClientQt::pageRect()

src/qt/src/3rdparty/webkit/Source/WebKit/qt/WebCoreSupport/PageClientQt.cpp

@@ -21,8 +21,10 @@
 #include "config.h"
 
 #include "PageClientQt.h"
+#if USE(ACCELERATED_COMPOSITING) && USE(TEXTURE_MAPPER)
 #include "TextureMapperQt.h"
 #include "texmap/TextureMapperPlatformLayer.h"
+#endif
 #include <QGraphicsScene>
 #include <QGraphicsView>
 #if defined(Q_WS_X11)