Fixed some issues with fullscreen dimming

- Always dim home stack and task fullscreen. The home stack could be
in split-screen mode, but we still want to dim dialogs that are
associated with the stack or task in fullscreen. The dialogs are not
really activities, but they are associated with the home stack for
things like dimming. Don't ask me why...
- Update the fullscreen dim layer bounds anytime the dim layer is
adjusted so we always have up-to-date bounds after rotation.

Bug: 28575624
Change-Id: I805c771153a2d25fb199bd9987bbf78a5967f6b9
diff --git a/services/core/java/com/android/server/wm/Task.java b/services/core/java/com/android/server/wm/Task.java
index efabe31..8f4197f 100644
--- a/services/core/java/com/android/server/wm/Task.java
+++ b/services/core/java/com/android/server/wm/Task.java
@@ -750,7 +750,11 @@
     }
 
     @Override
-    public boolean isFullscreen() {
+    public boolean dimFullscreen() {
+        return isHomeTask() || isFullscreen();
+    }
+
+    boolean isFullscreen() {
         if (useCurrentBounds()) {
             return mFullscreen;
         }