Use 8dp for fab elevation

Bug: 17897542
Change-Id: If734652e2157f820cfe738c310ac29a112d6265a
diff --git a/res-common/values/dimens.xml b/res-common/values/dimens.xml
index 57bcdfd..595d626 100644
--- a/res-common/values/dimens.xml
+++ b/res-common/values/dimens.xml
@@ -101,7 +101,7 @@
     <!-- Corner radius of the floating action button -->
     <dimen name="floating_action_button_radius">28dp</dimen>
     <!-- Z translation of the floating action button -->
-    <dimen name="floating_action_button_translation_z">2dp</dimen>
+    <dimen name="floating_action_button_translation_z">8dp</dimen>
     <!-- Padding to be applied to the bottom of lists to make space for the floating action
          button -->
     <dimen name="floating_action_button_list_bottom_padding">88dp</dimen>