Fix unit test helper

Change-Id: I161b451404bbecb30d8e229004786b9e9882e41c
diff --git a/java/proguard.flags b/java/proguard.flags
index 9096855..729f4ad 100644
--- a/java/proguard.flags
+++ b/java/proguard.flags
@@ -14,3 +14,7 @@
   void waitUntilUpdateDBDone();
   void waitForDictionaryLoading();
 }
+
+-keep class com.android.inputmethod.latin.AutoCorrection {
+  java.lang.CharSequence getAutoCorrectionWord();
+}