dart2js: Forbid # placeholders in JS function bodies.

pkg/compiler/lib/src/ssa/builder.dart

Index: pkg/compiler/lib/src/ssa/builder.dart
diff --git a/pkg/compiler/lib/src/ssa/builder.dart b/pkg/compiler/lib/src/ssa/builder.dart
index 2eae9e85caa2ddf9194ca3cc6c7457a4a3017203..55631447a81b4d35a1ac63ac7234d37667a01807 100644
--- a/pkg/compiler/lib/src/ssa/builder.dart
+++ b/pkg/compiler/lib/src/ssa/builder.dart
@@ -4154,6 +4154,13 @@ class SsaBuilder extends ast.Visitor
       return;
     }
 
+    if (native.HasCapturedPlaceholders.check(nativeBehavior.codeTemplate.ast)) {
+      reporter.reportErrorMessage(
+          node, MessageKind.GENERIC,
+          {'text':
+            'JS code must not use `#` inside functions'});

[Siggi Cherem (dart-lang), 2015/11/12 21:21:29]

maybe include your suggestion as well?

[sra1, 2015/11/12 22:23:26]

I tried. Providing examples is confusing because they look just like the bad
code.

+    }
+
     TypeMask ssaType =
         TypeMaskFactory.fromNativeBehavior(nativeBehavior, compiler);