Optimization of the request of the sentence level spell check

Change-Id: Ic89b0dd027bf0af6e8f1877043ae40baed48b2a4

Author: satok16

core/java/android/widget/SpellChecker.java

@@ -488,6 +488,10 @@ public void parse() {
                     editable.removeSpan(mRange);
                     return;
                 }
+                // Stop spell checking when there are no characters in the range.
+                if (wordEnd < start) {
+                    return;
+                }
                 wordStart = regionEnd;
                 // TODO: Find the start position of the sentence.
                 // Set span with the context