Use 8dp for fab elevation

This affects emergency dialer

Bug: 17897542
Change-Id: I585988c97c0e13072f4e1959555a8af029126296
diff --git a/res/values/dimens.xml b/res/values/dimens.xml
index 0dc916e..40f13e0 100644
--- a/res/values/dimens.xml
+++ b/res/values/dimens.xml
@@ -49,7 +49,7 @@
     <!-- 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">3dp</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>