dart2js: Register helpers for updating send to type variable.

pkg/compiler/lib/src/resolution/members.dart

 // Copyright (c) 2012, 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.
 
 library dart2js.resolution.members;
 
 import '../common/names.dart' show
     Selectors;
 import '../compiler.dart' show
     Compiler;
@@ skipping 1935 matching lines @@
           MessageKind.TYPE_VARIABLE_WITHIN_STATIC_MEMBER,
           {'typeVariableName': name},
           isError: true);
       registry.registerCompileTimeError(error);
       semantics = new StaticAccess.invalid(error);
       // TODO(johnniwinther): Clean up registration of elements and selectors
       // for this case.
     } else {
       semantics = new StaticAccess.typeParameterTypeLiteral(element);
     }
-    registry.registerClassUsingVariableExpression(element.enclosingClass);
-    registry.registerTypeVariableExpression();
+    registry.registerTypeVariableExpression(element);
 
     registry.useElement(node, element);
     registry.registerTypeLiteral(node, element.type);
 
     if (node.isCall) {
       CallStructure callStructure =
           resolveArguments(node.argumentsNode).callStructure;
       Selector selector = callStructure.callSelector;
       // TODO(23998): Remove this when all information goes through
       // the [SendStructure].
@@ skipping 32 matching lines @@
             MessageKind.IF_NULL_ASSIGNING_TYPE, const {});
         // TODO(23998): Remove these when all information goes through
         // the [SendStructure].
         registry.useElement(node.selector, element);
       } else {
         error = reportAndCreateErroneousElement(
             node.selector, name.text,
             MessageKind.ASSIGNING_TYPE, const {});
       }
 
+      if (node.isComplex) {

[Johnni Winther, 2015/09/15 13:23:40]

Maybe add the comment: "We read the type variable before trying write to it."

+        registry.registerTypeVariableExpression(element);
+      }
+
       // TODO(23998): Remove this when all information goes through
       // the [SendStructure].
       registry.useElement(node, error);
       registry.registerTypeLiteral(node, element.type);
       registry.registerThrowNoSuchMethod();
       semantics = new StaticAccess.typeParameterTypeLiteral(element);
     }
     return handleUpdate(node, name, semantics);
   }
 
@@ skipping 2644 matching lines @@
     }
     return const NoneResult();
   }
 }
 
 /// Looks up [name] in [scope] and unwraps the result.
 Element lookupInScope(Compiler compiler, Node node,
                       Scope scope, String name) {
   return Elements.unwrap(scope.lookup(name), compiler, node);
 }