Update status file for language/prefix_core_test.

dart/tests/language/language.status

Index: dart/tests/language/language.status
diff --git a/dart/tests/language/language.status b/dart/tests/language/language.status
index 3d8924e837059f78a5494ef42e4e7b3aa7633e8b..00ea1dd47b82b8b5a9b273542cf0bb7a2c581f71 100644
--- a/dart/tests/language/language.status
+++ b/dart/tests/language/language.status
@@ -50,6 +50,8 @@ closure_with_super_send_test: Fail # Issue 3197.
 super_closure_test: Fail # Issue 3197.
 parameter_initializer6_negative_test: Fail # Issue 3502
 
+prefix_core_test: Fail # Issue 3638.
+
 # DartC or Frog specific tests that should not be run by the VM
 *dartc_test: Skip
 *dartc_negative_test: Skip
@@ -419,6 +421,9 @@ static_field2_run_negative_test: Pass # but error is not correct
 constructor_redirect1_negative_test: Skip # Undiagnosed infinite loop.
 constructor_redirect2_negative_test: Skip # Undiagnosed infinite loop.
 
+[ $browser ]
+prefix_core_test: Fail # Issue 2264.
+
 [ $compiler == frog && $runtime == none ]
 *: Skip