Support patched generic methods.

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

 // Copyright (c) 2014, 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.
 
 library dart2js.js_backend.patch_resolver;
 
 import '../common.dart';
 import '../common/resolution.dart' show Resolution;
 import '../common/tasks.dart' show CompilerTask;
 import '../compiler.dart' show Compiler;
@@ skipping 88 matching lines @@
                     {'parameterName': patchParameter.name}),
               ]);
         }
       }
     }
   }
 
   void checkMatchingPatchSignatures(
       FunctionElement origin, FunctionElement patch) {
     // TODO(johnniwinther): Show both origin and patch locations on errors.
+    FunctionExpression originTree = origin.node;
     FunctionSignature originSignature = origin.functionSignature;
     FunctionExpression patchTree = patch.node;
     FunctionSignature patchSignature = patch.functionSignature;
 
+    if ('${originTree.typeVariables}' != '${patchTree.typeVariables}') {
+      reporter.withCurrentElement(patch, () {
+        Node errorNode = patchTree.typeVariables != null
+            ? patchTree.typeVariables
+            : patchTree;
+        reporter.reportError(
+            reporter.createMessage(
+                errorNode,
+                MessageKind.PATCH_TYPE_VARIABLES_MISMATCH,
+                {'methodName': origin.name}),
+            [reporter.createMessage(origin, MessageKind.THIS_IS_THE_METHOD)]);
+      });
+    }
     if (originSignature.type.returnType != patchSignature.type.returnType) {
       reporter.withCurrentElement(patch, () {
         Node errorNode =
             patchTree.returnType != null ? patchTree.returnType : patchTree;
         reporter.reportErrorMessage(
             errorNode, MessageKind.PATCH_RETURN_TYPE_MISMATCH, {
           'methodName': origin.name,
           'originReturnType': originSignature.type.returnType,
           'patchReturnType': patchSignature.type.returnType
         });
@@ skipping 34 matching lines @@
           'originParameterCount': originSignature.optionalParameterCount,
           'patchParameterCount': patchSignature.optionalParameterCount
         });
       });
     } else {
       checkMatchingPatchParameters(origin, originSignature.optionalParameters,
           patchSignature.optionalParameters);
     }
   }
 }