cps_ir: interceptor calling convention, operator== prologue

pkg/compiler/lib/src/cps_ir/cps_ir_nodes.dart

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 // IrNodes are kept in a separate library to have precise control over their
 // dependencies on other parts of the system.
 library dart2js.ir_nodes;
 
 import '../constants/expressions.dart';
 import '../constants/values.dart' as values show ConstantValue;
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 /// with a different implementation, the overriding implementation is bypassed
 /// and [target]'s implementation is invoked.
 ///
 /// As with [InvokeMethod], this can be used to invoke a method, operator,
 /// getter, setter, or index getter/setter.
 ///
 /// If it is known that [target] does not use its receiver argument, then
 /// [receiver] may refer to a null constant primitive. This happens for direct
 /// invocations to intercepted methods, where the effective receiver is instead
 /// passed as a formal parameter.
+/// TODO(sra): Review. A direct call to a method that is mixed into a native
+/// class will still require an explicit argument.
 ///
 /// When targeting Dart, this instruction is used to represent super calls.
 /// Here, [receiver] must always be a reference to `this`, and [target] must be
 /// a method that is available in the super class.
 class InvokeMethodDirectly extends Expression implements Invoke {
   Reference<Primitive> receiver;
   final Element target;
   final Selector selector;
   final Reference<Continuation> continuation;
   final List<Reference<Primitive>> arguments;
@@ skipping 1154 matching lines @@
   }
 
   void visitReifyRuntimeType(ReifyRuntimeType node) {
     visitReference(node.value);
   }
 
   void visitReadTypeVariable(ReadTypeVariable node) {
     visitReference(node.target);
   }
 }