Cleanup before fixing getTextAfterCursor().

We never delete text after the cursor, so constrain the API accordingly.
Define the number of characters to read before and after.
Set them to reasonable values.
The next CL will start caching text after the cursor.

Bug 21926256.

Change-Id: Idd58daf68614de4a69344aa3c8a4323720c5d3a0
2 files changed