Fix NPE in KeyboardSwitcher while orientation change

This is a follow up of I8a737e2b73.

Bug: 14981300
Bug: 14419121
Change-Id: I87f910adbff248d9606d074c351aa951c9539163

java/src/com/android/inputmethod/keyboard/KeyboardSwitcher.java

@@ -254,7 +254,7 @@ public final class KeyboardSwitcher implements KeyboardState.SwitchActions {
     // Implements {@link KeyboardState.SwitchActions}.
     @Override
     public void setEmojiKeyboard() {
-        final Keyboard keyboard = mKeyboardView.getKeyboard();
+        final Keyboard keyboard = mKeyboardLayoutSet.getKeyboard(KeyboardId.ELEMENT_ALPHABET);
         mMainKeyboardFrame.setVisibility(View.GONE);
         mEmojiPalettesView.startEmojiPalettes(
                 mKeyboardTextsSet.getText(KeyboardTextsSet.SWITCH_TO_ALPHA_KEY_LABEL),