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/row_qwerty4.xml b/java/res/xml/row_qwerty4.xml
index 509092d..5bc104f 100644
--- a/java/res/xml/row_qwerty4.xml
+++ b/java/res/xml/row_qwerty4.xml
@@ -28,7 +28,7 @@
             latin:keyStyle="toSymbolKeyStyle"
             latin:keyWidth="15%p" />
         <include
-            latin:keyboardLayout="@xml/key_f1" />
+            latin:keyboardLayout="@xml/key_comma" />
         <include
             latin:keyXPos="25%p"
             latin:keyboardLayout="@xml/key_space_5kw" />