Add default capacity parameter to InputPointers' constructor

.../src/com/android/inputmethod/keyboard/PointerTracker.java

.../android/inputmethod/keyboard/internal/GestureStroke.java

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

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

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

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