Fix 19029: handle special case when on-handler is empty in polymer, add better

pkg/polymer/lib/src/build/script_compactor.dart

Index: pkg/polymer/lib/src/build/script_compactor.dart
diff --git a/pkg/polymer/lib/src/build/script_compactor.dart b/pkg/polymer/lib/src/build/script_compactor.dart
index efd3571e6c34d95c2b11e114f1b4bac0a9ef92e5..b633360cb27610da7432724910bb1394b32d6a52 100644
--- a/pkg/polymer/lib/src/build/script_compactor.dart
+++ b/pkg/polymer/lib/src/build/script_compactor.dart
@@ -514,6 +514,7 @@ class _HtmlExtractor extends TreeVisitor {
   void _addExpression(String stringExpression, bool inEvent, bool isTwoWay) {
     if (inEvent) {
       if (!stringExpression.startsWith("@")) {

[Jennifer Messerly, 2014/05/29 00:27:42]

fyi -- should be trimming this if we aren't already

[Siggi Cherem (dart-lang), 2014/05/29 01:04:21]

good question - these are being trimmed in the mustache parser, I added a couple
test cases to make sure we don't regress.

+        if (stringExpression == '') return;
         generator.addGetter(stringExpression);
         generator.addSymbol(stringExpression);
         return;