Don't dispatchDetachedFromWindow() if the View was not attached.

Change-Id: I36cb697be76c8c03497284563dc339c5367559c6
diff --git a/core/java/android/view/ViewRoot.java b/core/java/android/view/ViewRoot.java
index ad9e6863..e228537 100644
--- a/core/java/android/view/ViewRoot.java
+++ b/core/java/android/view/ViewRoot.java
@@ -1780,7 +1780,7 @@
     }
 
     void dispatchDetachedFromWindow() {
-        if (mView != null) {
+        if (mView != null && mView.mAttachInfo != null) {
             mView.dispatchDetachedFromWindow();
         }