make sure to repaint the screen when unblank()ing

Change-Id: I38e3a8e6bb31ef3d2f1fcaec7490cb92a4427db2
diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index ca3c216..fbf2873 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -1746,6 +1746,8 @@
     getHwComposer().acquire();
     hw->acquireScreen();
     mEventThread->onScreenAcquired();
+    mVisibleRegionsDirty = true;
+    repaintEverything();
 }
 
 void SurfaceFlinger::onScreenReleased() {