Fix: Drag handle isn't updated after crossing bidi boundary.

mDrawable is updated, but it was not re-drawn properly.
postInvalidate() should be called when the drawable is
updated.

Bug: 21141841
Change-Id: Icb3ddf18d05285ffa8758a9be256482d594ab8ed

core/java/android/widget/Editor.java

@@ -3426,9 +3426,13 @@ public class Editor {
         protected void updateDrawable() {
             final int offset = getCurrentCursorOffset();
             final boolean isRtlCharAtOffset = mTextView.getLayout().isRtlCharAt(offset);
+            final Drawable oldDrawable = mDrawable;
             mDrawable = isRtlCharAtOffset ? mDrawableRtl : mDrawableLtr;
             mHotspotX = getHotspotX(mDrawable, isRtlCharAtOffset);
             mHorizontalGravity = getHorizontalGravity(isRtlCharAtOffset);
+            if (oldDrawable != mDrawable) {
+                postInvalidate();
+            }
         }
 
         protected abstract int getHotspotX(Drawable drawable, boolean isRtlRun);