Revert "Hide shelf in 2-Button Landscape"

This reverts commit 9b5795a579.

Reason for revert: b/155090034

Change-Id: If7decd54965a680d50e4474fb279ebe0002441bb

src/com/android/launcher3/InsettableFrameLayout.java

@@ -91,9 +91,6 @@ public class InsettableFrameLayout extends FrameLayout implements Insettable {
     @Override
     public void onViewAdded(View child) {
         super.onViewAdded(child);
-        if (!isAttachedToWindow()) {
-            return;
-        }
         setFrameLayoutChildInsets(child, mInsets, new Rect());
     }