dart2js cps: Bugfix in operator specialization.

pkg/compiler/lib/src/cps_ir/type_propagation.dart

Index: pkg/compiler/lib/src/cps_ir/type_propagation.dart
diff --git a/pkg/compiler/lib/src/cps_ir/type_propagation.dart b/pkg/compiler/lib/src/cps_ir/type_propagation.dart
index 67159305c2afd2ff430ca50e70d425ddd132dddc..f60b28ab55bf056af70a5fd00ca0315e8c0a0983 100644
--- a/pkg/compiler/lib/src/cps_ir/type_propagation.dart
+++ b/pkg/compiler/lib/src/cps_ir/type_propagation.dart
@@ -682,8 +682,10 @@ class TransformingVisitor extends RecursiveVisitor {
         }
         else if (lattice.isDefinitelyString(left, allowNull: false) &&
                  lattice.isDefinitelyString(right, allowNull: false)) {
-          return replaceWithBinary(BuiltinOperator.StringConcatenate,
-                                   leftArg, rightArg);
+          if (node.selector.name == '+') {

[karlklose, 2015/07/07 12:48:00]

You could also align this with the structure of the handling of 'operator =='.

+            return replaceWithBinary(BuiltinOperator.StringConcatenate,
+                                     leftArg, rightArg);
+          }
         }
       }
     }