Discard framebuffer commands when we redraw the entire buffer

Change-Id: I32e3014832cbd3bdbace8c3d2206eb20a2002d64
diff --git a/libs/hwui/DisplayListRenderer.cpp b/libs/hwui/DisplayListRenderer.cpp
index 755170f..c3444e6 100644
--- a/libs/hwui/DisplayListRenderer.cpp
+++ b/libs/hwui/DisplayListRenderer.cpp
@@ -1412,8 +1412,12 @@
     mSnapshot = new Snapshot(mFirstSnapshot,
             SkCanvas::kMatrix_SaveFlag | SkCanvas::kClip_SaveFlag);
     mSaveCount = 1;
+
     mSnapshot->setClip(0.0f, 0.0f, mWidth, mHeight);
+    mDirtyClip = opaque;
+
     mRestoreSaveCount = -1;
+
     return DrawGlInfo::kStatusDone; // No invalidate needed at record-time
 }