Compose: Set focus to the To field by default

We initialize the focus with setNewMessageFocus(), but it's only called
from processSourceMessage() (for EDIT_DRAFT) initFromIntent() (for other
actions, except for "new draft").  We didn't intialize the focus for new
drafts.  Let's just get the To field to get the focus by default to
cover this case.

Bug 4048238

Change-Id: I50cd69b8813198c96beab2025576d390520dc6a4

src/com/android/email/activity/MessageCompose.java

@@ -593,6 +593,7 @@ public class MessageCompose extends Activity implements OnClickListener, OnFocus
         mMessageContentView.setOnFocusChangeListener(this);
 
         updateAttachmentContainer();
+        mToView.requestFocus();
     }
 
     /**