Fix unit tests by adding @UsedForTesting.

Change-Id: I8497d6cf446297bc8c15e9d9818078b1026a8c51

java/src/com/android/inputmethod/latin/makedict/ProbabilityInfo.java

@@ -16,6 +16,7 @@
 
 package com.android.inputmethod.latin.makedict;
 
+import com.android.inputmethod.annotations.UsedForTesting;
 import com.android.inputmethod.latin.BinaryDictionary;
 import com.android.inputmethod.latin.utils.CombinedFormatUtils;
 
@@ -30,6 +31,7 @@ public final class ProbabilityInfo {
     public final int mLevel;
     public final int mCount;
 
+    @UsedForTesting
     public static ProbabilityInfo max(final ProbabilityInfo probabilityInfo1,
             final ProbabilityInfo probabilityInfo2) {
         if (probabilityInfo1 == null) {

java/src/com/android/inputmethod/latin/makedict/WordProperty.java

@@ -42,6 +42,7 @@ public final class WordProperty implements Comparable<WordProperty> {
 
     private int mHashCode = 0;
 
+    @UsedForTesting
     public WordProperty(final String word, final ProbabilityInfo probabilityInfo,
             final ArrayList<WeightedString> shortcutTargets,
             final ArrayList<WeightedString> bigrams,