Text traversal at various granularities.

1. Implementing text content navigation at various granularities.
   For views that have content description but no text the
   content description is the traversed at character and word
   granularities. For views that inherit from TextView the
   supported granularities are character, word, line, and page.

bug:5932640

Conflicts:

	core/java/android/view/View.java

Conflicts:

	core/java/android/view/View.java

Change-Id: I66d1e16ce9ac5d6b49f036b17c087b2a7075e4c0