Optimize DDC private library files.

pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/errors.dart

Index: pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/errors.dart
diff --git a/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/errors.dart b/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/errors.dart
index 14f89cf55ef8da5fe9efde43a77272f1f50dbff0..2697437a60df6f7731840fef2d439e33bcd6c33f 100644
--- a/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/errors.dart
+++ b/pkg/dev_compiler/tool/input_sdk/private/ddc_runtime/errors.dart
@@ -21,6 +21,11 @@ void ignoreAllErrors(bool flag) {
   JS('', 'dart.__ignoreAllErrors = #', flag);
 }
 
+argumentError(value) {
+  if (JS('bool', 'dart.__trapRuntimeErrors')) JS('', 'debugger');
+  throw new ArgumentError.value(value);
+}
+
 throwCastError(object, actual, type) {
   var found = typeName(actual);
   var expected = typeName(type);