Fix for issue 28196 - constant interceptors for mixin applications

pkg/compiler/lib/src/js_backend/namer.dart

Index: pkg/compiler/lib/src/js_backend/namer.dart
diff --git a/pkg/compiler/lib/src/js_backend/namer.dart b/pkg/compiler/lib/src/js_backend/namer.dart
index d4813ad51173c3d0c05f91ec07b8d8a1138f1232..784a9405af9e2179f1d422f8435df81b0c35e494 100644
--- a/pkg/compiler/lib/src/js_backend/namer.dart
+++ b/pkg/compiler/lib/src/js_backend/namer.dart
@@ -1892,7 +1892,8 @@ class ConstantNamingVisitor implements ConstantValueVisitor {
 
   @override
   void visitInterceptor(InterceptorConstantValue constant, [_]) {
-    addRoot(constant.cls.name);
+    // The class name for mixin applications contain '+' signs (issue 28196).
+    addRoot(constant.cls.name.replaceAll('+', '_'));
     add('methods');
   }