Fix android.text.cts.SpannableStringBuilderTest#testReplace2

The test was failing because recent versions now throw NPE rather than
AIOOB. Given that the argument is null, I think NPE is appropriate, so I
am fixing the test to accept it as well.

Change-Id: I01caa93b0b737659b3b01a97decc729156994e88
diff --git a/tests/tests/text/src/android/text/cts/SpannableStringBuilderTest.java b/tests/tests/text/src/android/text/cts/SpannableStringBuilderTest.java
index cfc000d..4895ca9 100644
--- a/tests/tests/text/src/android/text/cts/SpannableStringBuilderTest.java
+++ b/tests/tests/text/src/android/text/cts/SpannableStringBuilderTest.java
@@ -259,6 +259,8 @@
             fail("should throw IndexOutOfBoundsException here");
         } catch (IndexOutOfBoundsException e) {
             // expected exception
+        } catch (NullPointerException e) {
+            // expected exception
         }
     }