Truncate verbose source print.

dart/site/try/poi/poi.dart

Index: dart/site/try/poi/poi.dart
diff --git a/dart/site/try/poi/poi.dart b/dart/site/try/poi/poi.dart
index d7ae82d33a22666a1c4d8b90cd22cca37a06fd53..69fcea21d70250539a1420dbd7d3f361dc9676d7 100644
--- a/dart/site/try/poi/poi.dart
+++ b/dart/site/try/poi/poi.dart
@@ -197,7 +197,9 @@ api.CompilerInputProvider simulateMutation(
         }
         printVerbose('Not using cached version of $cachedFileName');
         cache = new io.File(cachedFileName).readAsBytes().then((data) {
-          printVerbose('Read file $cachedFileName: ${UTF8.decode(data)}');
+          printVerbose(
+              'Read file $cachedFileName: '
+              '${UTF8.decode(data.sublist(0, 100), allowMalformed: true)}...');
           return data;
         });
         count++;