Fix the bottom row of tablet keyboard layout

This CL eliminates "_" and "/" keys from the bottom row of tablet
keyboard.  This CL also reorganizes the bottom row of tablet Dvorak
keyboard.

Bug: 16603887
Change-Id: Ic1570836dea1a475bed5d43aeb6a351507bf5428
diff --git a/java/res/xml/key_period.xml b/java/res/xml/key_period.xml
index e1d4bbd..fc27c02 100644
--- a/java/res/xml/key_period.xml
+++ b/java/res/xml/key_period.xml
@@ -48,6 +48,14 @@
                 latin:moreKeys="!text/morekeys_punctuation"
                 latin:backgroundType="functional" />
         </case>
+        <case
+            latin:keyboardLayoutSet="dvorak"
+        >
+            <Key
+                latin:keySpec="z"
+                latin:keyLabelFlags="hasPopupHint"
+                latin:moreKeys="!text/morekeys_punctuation,!text/morekeys_z" />
+        </case>
         <default>
             <Key
                 latin:keySpec="!text/keyspec_period"