Delete fillViewport attribute from RecyclerView.

It's an attribute for ScrollView, and a no-op on RecyclerView.

Review-Url: https://codereview.chromium.org/2389263008
Cr-Commit-Position: refs/heads/master@{#423850}

chrome/android/java/res/layout/new_tab_page_recycler_view.xml

@@ -6,7 +6,6 @@
 <org.chromium.chrome.browser.ntp.cards.NewTabPageRecyclerView
     xmlns:android="http://schemas.android.com/apk/res/android"
     android:background="@color/ntp_material_design_bg"
-    android:fillViewport="true"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:focusable="true"