Remove support for the DeferredLibrary annotation and remove tests of it

tests/lib/lib.status

Index: tests/lib/lib.status
diff --git a/tests/lib/lib.status b/tests/lib/lib.status
index 4ba15f7c5ffef8eb476d3631b0155890d66930ff..17c17a750b83e41ffb557ebf3f4fbe4dc4076a1b 100644
--- a/tests/lib/lib.status
+++ b/tests/lib/lib.status
@@ -281,12 +281,13 @@ convert/streamed_conversion_utf8_decode_test: Skip # Times out or passes. Issue
 mirrors/lazy_static_test: Skip # Times out. Issue 19127
 mirrors/mirrors_reader_test: Skip # Times out. Issue 19127
 
-[ $compiler == dart2dart || ($compiler == none && ($runtime == drt || $runtime == dartium || $runtime == vm || $runtime == ContentShellOnAndroid)) ]
-# Deferred loading is not implemented in the VM so the error-handling will never be triggered.
-async/deferred/deferred_fail_to_load_test: Fail
-# Deferred loading is not implemented in the VM so the error-handling will never be triggered.
-# Issue 13921: spawnFunction is not allowed on Dartium's DOM thread.
-async/deferred/deferred_in_isolate_test: Fail
+[ $compiler == dart2dart ]
+# Deferred loading is not supported by dart2dart.
+async/deferred/deferred_in_isolate_test: Skip # Issue 17523
+
+[ $compiler == none && ($runtime == drt || $runtime == dartium || $runtime == ContentShellOnAndroid) ]
+# Dart vm does not support spawn from a dom-enabled isolate.
+async/deferred/deferred_in_isolate_test: RuntimeError # Issue 16209
 
 [ $compiler == dart2js && ($runtime == ie9 || $runtime == ie10 || $runtime == jsshell) ]
 async/schedule_microtask_test: Fail # Issue 9002