Add an error when a type parameter from a generic function is used in an is test

pkg/analyzer/lib/src/error/codes.dart

Index: pkg/analyzer/lib/src/error/codes.dart
diff --git a/pkg/analyzer/lib/src/error/codes.dart b/pkg/analyzer/lib/src/error/codes.dart
index 10c39cb2ac00cff925a23703233004472955b1f5..c73de060edbe6a6c0bf9b81cc8ea1a53e6e4d55c 100644
--- a/pkg/analyzer/lib/src/error/codes.dart
+++ b/pkg/analyzer/lib/src/error/codes.dart
@@ -4437,6 +4437,19 @@ class StaticWarningCode extends ErrorCode {
           "changing the import to not be deferred.");
 
   /**
+   * Not yet spec'd.
+   *
+   * Parameters:
+   * 0: the name of the generic function's type parameter that is being used in
+   *    an `is` expression
+   */
+  static const StaticWarningCode TYPE_ANNOTATION_GENERIC_FUNCTION_PARAMETER =
+      const StaticWarningCode(
+          'TYPE_ANNOTATION_GENERIC_FUNCTION_PARAMETER',
+          "The type parameter '{0}' can't be used in a type test.",
+          "Try using a different type.");
+
+  /**
    * 12.31 Type Test: It is a static warning if <i>T</i> does not denote a type
    * available in the current lexical scope.
    */