Fix crash on calling removeSelection with showing selection handlers

A crash occured on updating after calling removeSelection with showing
selection handlers. This was because some selection-handler code didn't
consider the case the selection index was -1 (-1 means there is no selection).
This patch fixes this crash.

Bug: 23299977
Change-Id: I736d315e073f773aec597522203015205a8da42b

core/java/android/widget/Editor.java

@@ -4253,10 +4253,14 @@ public class Editor {
             positionAtCursorOffset(offset, false);
         }
 
+        /**
+         * @param offset Cursor offset. Must be in [-1, length].
+         * @param parentScrolled If the parent has been scrolled or not.
+         */
         @Override
         protected void positionAtCursorOffset(int offset, boolean parentScrolled) {
             super.positionAtCursorOffset(offset, parentScrolled);
-            mInWord = !getWordIteratorWithText().isBoundary(offset);
+            mInWord = (offset != -1) && !getWordIteratorWithText().isBoundary(offset);
         }
 
         @Override
@@ -4489,10 +4493,14 @@ public class Editor {
             positionAtCursorOffset(offset, false);
         }
 
+        /**
+         * @param offset Cursor offset. Must be in [-1, length].
+         * @param parentScrolled If the parent has been scrolled or not.
+         */
         @Override
         protected void positionAtCursorOffset(int offset, boolean parentScrolled) {
             super.positionAtCursorOffset(offset, parentScrolled);
-            mInWord = !getWordIteratorWithText().isBoundary(offset);
+            mInWord = (offset != -1) && !getWordIteratorWithText().isBoundary(offset);
         }
 
         @Override