Implement is-Operator for interfaces.

frog/leg/emitter.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * Generates the code for all used classes in the program. Static fields (even
  * in classes) are ignored, since they can be treated as non-class elements.
  *
  * The code for the containing (used) methods must exist in the [:universe:].
  */
@@ skipping 215 matching lines @@
       if (member.isInstanceMember()) {
         addInstanceMember(member, prototype, buffer);
       }
     }
     for (Element member in classElement.backendMembers) {
       if (member.isInstanceMember()) {
         addInstanceMember(member, prototype, buffer);
       }
     }
     buffer.add('$prototype.${namer.operatorIs(classElement)} = true;\n');
+    for (Type ifc in classElement.interfaces) {
+      buffer.add('$prototype.${namer.operatorIs(ifc.element)} = true;\n');
+    }
   }
 
   void emitClasses(StringBuffer buffer) {
     Set seenClasses = new Set<ClassElement>();
     for (ClassElement element in compiler.universe.instantiatedClasses) {
       generateClass(element, buffer, seenClasses);
     }
   }
 
   void emitStaticFunctionsWithNamer(StringBuffer buffer,
@@ skipping 110 matching lines @@
       emitStaticFunctions(buffer);
       emitStaticFinalFieldInitializations(buffer);
       buffer.add('var ${namer.CURRENT_ISOLATE} = new ${namer.ISOLATE}();\n');
       Element main = compiler.mainApp.find(Compiler.MAIN);
       buffer.add('${namer.isolateAccess(main)}();\n');
       compiler.assembledCode = buffer.toString();
     });
     return compiler.assembledCode;
   }
 }