Add Dictionary.isInDictionary().

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

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

...c/com/android/inputmethod/latin/DictionaryCollection.java

...android/inputmethod/latin/ExpandableBinaryDictionary.java

...m/android/inputmethod/latin/ReadOnlyBinaryDictionary.java

...rsonalization/DecayingExpandableBinaryDictionaryBase.java

...thod/latin/personalization/PersonalizationDictionary.java

...utmethod/latin/personalization/UserHistoryDictionary.java

.../android/inputmethod/latin/spellcheck/DictionaryPool.java

...ellcheck/SynchronouslyLoadedContactsBinaryDictionary.java

...n/spellcheck/SynchronouslyLoadedUserBinaryDictionary.java

...hod/latin/personalization/UserHistoryDictionaryTests.java