Suppress lints on synthetic nodes/tokens (#193).

test/_data/synthetic/synthetic.dart

Index: test/_data/synthetic/synthetic.dart
diff --git a/test/_data/synthetic/synthetic.dart b/test/_data/synthetic/synthetic.dart
new file mode 100644
index 0000000000000000000000000000000000000000..31c60cd004112854568cc3739ea6c3797a6ae221
--- /dev/null
+++ b/test/_data/synthetic/synthetic.dart
@@ -0,0 +1,5 @@
+// Verifies that synthetic nodes don't get lints.
+// `XXX` below is synthetic

[Brian Wilkerson, 2016/03/01 21:26:54]

That can't be true because synthetic tokens are always zero length. I think
what's happening is that we're inserting a synthetic token after 'XXX' and
that's what's causing the lint to fire.

[pquitslund, 2016/03/01 21:30:01]

You're right!  I just figured that out myself (see screenshot here:
https://github.com/dart-lang/sdk/issues/25876).

Will fix.

+// See: https://github.com/dart-lang/linter/issues/193
+void main() { }
+XXX