Fix rti encoding of generic methods

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

Index: pkg/compiler/lib/src/js_backend/runtime_types.dart
diff --git a/pkg/compiler/lib/src/js_backend/runtime_types.dart b/pkg/compiler/lib/src/js_backend/runtime_types.dart
index 590e99f5ec32df5bb9d23de9eceed7dd7bda07bf..65b9e16c4e40f2b5d0f3ac2b066bd98b88dbd668 100644
--- a/pkg/compiler/lib/src/js_backend/runtime_types.dart
+++ b/pkg/compiler/lib/src/js_backend/runtime_types.dart
@@ -609,8 +609,10 @@ class _RuntimeTypesEncoder implements RuntimeTypesEncoder {
   jsAst.Expression getTypeRepresentation(
       DartType type, OnVariableCallback onVariable,
       [ShouldEncodeTypedefCallback shouldEncodeTypedef]) {
+    // GENERIC_METHODS: When generic method support is complete enough to
+    // include a runtime value for method type variables this must be updated.
     return representationGenerator.getTypeRepresentation(
-        type, onVariable, shouldEncodeTypedef);
+        type.dynamifyMethodTypeVariableType, onVariable, shouldEncodeTypedef);
   }
 
   @override