Remove support for 'argument definitions test' from dart2js.

sdk/lib/_internal/lib/core_patch.dart

Index: sdk/lib/_internal/lib/core_patch.dart
diff --git a/sdk/lib/_internal/lib/core_patch.dart b/sdk/lib/_internal/lib/core_patch.dart
index dec98f1ce6f81b0987ebfacddada4ed95e6bfe94..08d4be45bf2cb36df90b64646fc64caaba42cc17 100644
--- a/sdk/lib/_internal/lib/core_patch.dart
+++ b/sdk/lib/_internal/lib/core_patch.dart
@@ -184,7 +184,7 @@ patch class Stopwatch {
 // Patch for List implementation.
 patch class List<E> {
   patch factory List([int length]) {
-    if (!?length) return Primitives.newGrowableList(0);
+    if (length == null) return Primitives.newGrowableList(0);
     // Explicit type test is necessary to protect Primitives.newFixedList in
     // unchecked mode.
     if ((length is !int) || (length < 0)) {