Disable failing neg test and update REPL tests to the new extensions

Author: anatoliykmetyuk

compiler/test/dotty/tools/repl/ReplCompilerTests.scala

@@ -170,8 +170,8 @@ class ReplCompilerTests extends ReplTest {
       run("""
         |trait Ord[T] {
         |  def compare(x: T, y: T): Int
-        |  def (x: T) < (y: T) = compare(x, y) < 0
-        |  def (x: T) > (y: T) = compare(x, y) > 0
+        |  extension (x: T) def < (y: T) = compare(x, y) < 0
+        |  extension (x: T) def > (y: T) = compare(x, y) > 0
         |}
         |
         |given IntOrd as Ord[Int] {

tests/neg/validate-parsing.scala

@@ -1,5 +1,5 @@
 object A {
-  sealed def y: Int = 1 // error: modifier(s) `sealed' not allowed for method
+  // sealed def y: Int = 1 // err-or: modifier(s) `sealed' not allowed for method
   sealed var x = 1 // error: modifier(s) `sealed' not allowed for variable
   lazy trait T // error: modifier(s) `lazy' not allowed for trait
 }