Fix a possible NPE.

This NPE's at least in unit tests.

Change-Id: I255ac5fec9502e4e5bd18cba1211cdf46c6cafc8

java/src/com/android/inputmethod/latin/TargetApplicationGetter.java

@@ -29,6 +29,7 @@ public class TargetApplicationGetter extends AsyncTask<String, Void, Application
             new LruCache<String, ApplicationInfo>(MAX_CACHE_ENTRIES);
 
     public static ApplicationInfo getCachedApplicationInfo(final String packageName) {
+        if (null == packageName) return null;
         return sCache.get(packageName);
     }
     public static void removeApplicationInfoCache(final String packageName) {