Handle integer overflow in BaseInputConnection

When IME tries to load input context with a large range like
[Integer.MAX_VALUE, Integer.MAX_VALUE], app might crash as current
implementation can't handle integer overflow well.

Fix the issue by guarding the range of the text after the cursor.

Test: BaseInputConnectionTest

BUG: 279670566
Fix: 279670566

Change-Id: I5e3df4f2288896cbd21f6c1a59b7e315c60029c4