Reset the dirty region after drawing in hardware.

Change-Id: I687419f2a95d5d7c51913467bd80249244102725
diff --git a/core/java/android/view/ViewRoot.java b/core/java/android/view/ViewRoot.java
index 79f1f5b..cce860b 100644
--- a/core/java/android/view/ViewRoot.java
+++ b/core/java/android/view/ViewRoot.java
@@ -1280,8 +1280,9 @@
         }
         
         if (mAttachInfo.mHardwareRenderer != null && mAttachInfo.mHardwareRenderer.isEnabled()) {
-            if (!dirty.isEmpty()) {
+            if (!dirty.isEmpty() || mIsAnimating) {
                 mAttachInfo.mHardwareRenderer.draw(mView, mAttachInfo, yoff);
+                dirty.setEmpty();
             }
 
             if (scrolling) {