dart2js: remove invalid case in generateParameterStubStatements in NativeEmitter.

pkg/compiler/lib/src/js_emitter/native_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.
 
 part of dart2js.js_emitter;
 
 class NativeEmitter {
 
   final Map<Element, ClassBuilder> cachedBuilders;
 
@@ skipping 315 matching lines @@
 
     String target;
     jsAst.Expression receiver;
     List<jsAst.Expression> arguments;
 
     assert(invariant(member, nativeMethods.contains(member)));
     // When calling a JS method, we call it with the native name, and only the
     // arguments up until the last one provided.
     target = member.fixedBackendName;
 
-    if (isInterceptedMethod) {
-      receiver = argumentsBuffer[0];
-      arguments = argumentsBuffer.sublist(1,
-          indexOfLastOptionalArgumentInParameters + 1);
-    } else {
-      receiver = js('this');
-      arguments = argumentsBuffer.sublist(0,
-          indexOfLastOptionalArgumentInParameters + 1);
-    }
+    assert(invariant(member, isInterceptedMethod));
+    receiver = argumentsBuffer[0];
+    arguments = argumentsBuffer.sublist(1,
+        indexOfLastOptionalArgumentInParameters + 1);
     statements.add(
         js.statement('return #.#(#)', [receiver, target, arguments]));
 
     return statements;
   }
 
   bool isSupertypeOfNativeClass(Element element) {
     if (element.isTypeVariable) {
       compiler.internalError(element, "Is check for type variable.");
       return false;
@@ skipping 114 matching lines @@
           }
     ''', {'info': infoAccess,
           'constructor': constructorAccess,
           'subclassRead': subclassRead,
           'interceptorsByTagAccess': interceptorsByTagAccess,
           'leafTagsAccess': leafTagsAccess,
           'nativeSuperclassTagName': embeddedNames.NATIVE_SUPERCLASS_TAG_NAME,
           'allowNativesSubclassing': true});
   }
 }