Fix AutofillValueTest#autofillEmptyTextValue.

The new added API for rich content(ag/9884022) denies to autofill
empty text. However, Autofill allows us to fill an empty text. We
should not cause a compatibility issue.

Bug: 159035197
Test: atest android.autofillservice.cts.AutofillValueTest#\
autofillEmptyTextValue
Test: atest FrameworksCoreTests:AutofillValueTest

Change-Id: Ieb5b82bfe4bf77abd151c61ea4cf9125b8fe61f5

core/java/android/widget/TextViewRichContentReceiver.java

@@ -116,9 +116,6 @@ final class TextViewRichContentReceiver implements RichContentReceiver<TextView>
     private static boolean onReceiveForAutofill(@NonNull TextView textView, @NonNull ClipData clip,
             @Flags int flags) {
         final CharSequence text = coerceToText(clip, textView.getContext(), flags);
-        if (text.length() == 0) {
-            return false;
-        }
         // First autofill it...
         textView.setText(text);
         // ...then move cursor to the end.