Fix unit tests (InputLogicTestsDeadKeys).

Change-Id: I9a3191548aa0a4e674d736bc10845b952fc9a1e8
diff --git a/java/src/com/android/inputmethod/event/DeadKeyCombiner.java b/java/src/com/android/inputmethod/event/DeadKeyCombiner.java
index 9d7cc05..7b89b04 100644
--- a/java/src/com/android/inputmethod/event/DeadKeyCombiner.java
+++ b/java/src/com/android/inputmethod/event/DeadKeyCombiner.java
@@ -218,7 +218,10 @@
     @Nonnull
     private static Event createEventChainFromSequence(final @Nonnull CharSequence text,
             @Nonnull final Event originalEvent) {
-        Event lastEvent = originalEvent;
+        if (text.length() <= 0) {
+            return originalEvent;
+        }
+        Event lastEvent = null;
         int codePoint = 0;
         for (int i = text.length(); i > 0; i -= Character.charCount(codePoint)) {
             codePoint = Character.codePointBefore(text, i);