Roll version to 0.5.6+2 (#29)

diff --git a/pubspec.yaml b/pubspec.yaml
index ae49cb0..ccd246d 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -1,5 +1,5 @@
 name: dart2js_info
-version: 0.5.6+1
+version: 0.5.6+2
 description: >
   Libraries and tools to process data produced when running dart2js with
   --dump-info.