b/5628018 Fix NPE in ExpandableTextView

Change-Id: If4ded8ba430f1c984821cb0333c485ad439c10f4
diff --git a/src/com/android/calendar/ExpandableTextView.java b/src/com/android/calendar/ExpandableTextView.java
index 026e3de..508528e 100644
--- a/src/com/android/calendar/ExpandableTextView.java
+++ b/src/com/android/calendar/ExpandableTextView.java
@@ -119,6 +119,9 @@
     }
 
     public CharSequence getText() {
+        if (mTv == null) {
+            return "";
+        }
         return mTv.getText();
     }
 }