Add compile flag for enabling the compostior

sky/engine/core/rendering/compositing/RenderLayerCompositor.cpp

Index: sky/engine/core/rendering/compositing/RenderLayerCompositor.cpp
diff --git a/sky/engine/core/rendering/compositing/RenderLayerCompositor.cpp b/sky/engine/core/rendering/compositing/RenderLayerCompositor.cpp
index f8e87d802010fad20fbbf72003af5a3f42aedd54..15a9b52c7ad2228569fa564c429a85f020f4d929 100644
--- a/sky/engine/core/rendering/compositing/RenderLayerCompositor.cpp
+++ b/sky/engine/core/rendering/compositing/RenderLayerCompositor.cpp
@@ -115,8 +115,11 @@ void RenderLayerCompositor::enableCompositingModeIfNeeded()
 
 bool RenderLayerCompositor::rootShouldAlwaysComposite() const
 {
-    // FIXME(sky): Remove
+#if ENABLE(COMPOSITOR)
     return true;
+#else
+    return false;
+#endif
 }
 
 void RenderLayerCompositor::updateAcceleratedCompositingSettings()
@@ -125,6 +128,15 @@ void RenderLayerCompositor::updateAcceleratedCompositingSettings()
     m_rootShouldAlwaysCompositeDirty = true;
 }
 
+bool RenderLayerCompositor::hasAcceleratedCompositing() const
+{
+#if ENABLE(COMPOSITOR)
+    return true;
+#else
+    return false;
+#endif
+}
+
 bool RenderLayerCompositor::layerSquashingEnabled() const
 {
     if (!RuntimeEnabledFeatures::layerSquashingEnabled())
@@ -210,7 +222,9 @@ void RenderLayerCompositor::updateIfNeeded()
     m_pendingUpdateType = CompositingUpdateNone;
 
     if (!hasAcceleratedCompositing()) {
+#if ENABLE(COMPOSITOR)
         updateWithoutAcceleratedCompositing(updateType);
+#endif
         return;
     }