Check for a passed-in type argument vector in the prolog of generic functions.

runtime/lib/object_patch.dart

Index: runtime/lib/object_patch.dart
diff --git a/runtime/lib/object_patch.dart b/runtime/lib/object_patch.dart
index 603911f3ee7034b0895c0baae47e38db80673eda..077a5d8d4a1236057526aa5378b72fcec631a82f 100644
--- a/runtime/lib/object_patch.dart
+++ b/runtime/lib/object_patch.dart
@@ -57,9 +57,15 @@ class Object {
 
   static bool _haveSameRuntimeType(a, b) native "Object_haveSameRuntimeType";
 
+  // Prepend the parent type arguments (maybe null) to the function type
+  // arguments (may be null). The result is null if both input vectors are null
+  // or is a newly allocated and canonicalized vector of length 'len'.
+  static _prependTypeArguments(functionTypeArguments, parentTypeArguments, len)

[Vyacheslav Egorov (Google), 2017/06/15 14:05:44]

Is it possible to put this into dart:_internal instead of placing it on Object?
I find it a bit confusing that we put a lot of helpers on Object.

[regis, 2017/06/15 21:38:26]

Yes, definitely. I did not know of the existence of internal_patch.dart.

+      native "Object_prependTypeArguments";
+
   // Call this function instead of inlining instanceof, thus collecting
   // type feedback and reducing code size of unoptimized code.
-  bool _instanceOf(instantiator_type_arguments, function_type_arguments, type)
+  bool _instanceOf(instantiatorTypeArguments, functionTypeArguments, type)
       native "Object_instanceOf";
 
   // Group of functions for implementing fast simple instance of.
@@ -69,7 +75,7 @@ class Object {
 
   // Call this function instead of inlining 'as', thus collecting type
   // feedback. Returns receiver.
-  _as(instantiator_type_arguments, function_type_arguments, type)
+  _as(instantiatorTypeArguments, functionTypeArguments, type)
       native "Object_as";
 
   static _symbolMapToStringMap(Map<Symbol, dynamic> map) {