Add expected failures for the new conformance test issues. (apple#1822)

Author: thomasvl

Sources/Conformance/failure_list_swift.txt

@@ -2,3 +2,11 @@
 Recommended.*.JsonInput.FieldNameDuplicate # Should have failed to parse, but didn't.
 Recommended.*.JsonInput.FieldNameDuplicateDifferentCasing1 # Should have failed to parse, but didn't.
 Recommended.*.JsonInput.FieldNameDuplicateDifferentCasing2 # Should have failed to parse, but didn't.
+
+# Tracking in #1821
+Required.*.DurationProtoNanosTooLarge.JsonOutput # Should have failed to serialize, but didn't.
+Required.*.DurationProtoNanosTooSmall.JsonOutput # Should have failed to serialize, but didn't.
+Required.*.DurationProtoNanosWrongSign.JsonOutput # Should have failed to serialize, but didn't.
+Required.*.DurationProtoNanosWrongSignNegativeSecs.JsonOutput # Should have failed to serialize, but didn't.
+Required.*.TimestampProtoNanoTooLarge.JsonOutput # Should have failed to serialize, but didn't.
+Required.*.TimestampProtoNegativeNanos.JsonOutput # Should have failed to serialize, but didn't.