Remove textIsSelectable to work around b/16324602.

Change-Id: I515a1d7175d321e452034b9e9cbad1522389f2e5
diff --git a/res/values/styles.xml b/res/values/styles.xml
index 18b5fa9..30978ea 100644
--- a/res/values/styles.xml
+++ b/res/values/styles.xml
@@ -273,7 +273,6 @@
 
     <style name="ConversationSubjectStyle">
         <item name="android:textColor">@color/conversation_view_text_color_dark</item>
-        <item name="android:textIsSelectable">true</item>
         <item name="android:textSize">@dimen/conversation_header_font_size</item>
     </style>