Fixed SSB. Correct broadcast of removed spans' positions

Found while tracking bug 6326750

A bug in the SpannableStringBuilderSpanTest JUnit CTS test was hiding
this problem.

Also removed the instanceof test on SpanWatcher. All spans, including
those implementing this interface should be copied.

Change-Id: I5233818fb0c08ab56477720db932a5be453e88ee
1 file changed