Reverts the following two commits:

pkg/compiler/lib/src/ssa/graph_builder.dart

 // Copyright (c) 2016, 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.
 
 import '../closure.dart';
 import '../common.dart';
 import '../common/codegen.dart' show CodegenRegistry;
 import '../compiler.dart';
 import '../constants/constant_system.dart';
 import '../elements/resolution_types.dart';
@@ skipping 245 matching lines @@
 
   void visitVoidType(ResolutionVoidType type, GraphBuilder builder) {
     ClassElement cls = builder.backend.helpers.VoidRuntimeType;
     builder.push(new HVoidType(type, new TypeMask.exact(cls, closedWorld)));
   }
 
   void visitTypeVariableType(
       ResolutionTypeVariableType type, GraphBuilder builder) {
     ClassElement cls = builder.backend.helpers.RuntimeType;
     TypeMask instructionType = new TypeMask.subclass(cls, closedWorld);
-
-    // TODO(floitsch): this hack maps type variables of generic function
-    // typedefs to dynamic. For example: `typedef F = Function<T>(T)`.
-    if (type is MethodTypeVariableType) {
-      visitDynamicType(const ResolutionDynamicType(), builder);
-      return;
-    }
-
     if (!builder.sourceElement.enclosingElement.isClosure &&
         builder.sourceElement.isInstanceMember) {
       HInstruction receiver = builder.localsHandler.readThis();
       builder.push(new HReadTypeVariable(type, receiver, instructionType));
     } else {
       builder.push(new HReadTypeVariable.noReceiver(
           type,
           builder.typeBuilder
               .addTypeVariableReference(type, builder.sourceElement),
           instructionType));
@@ skipping 55 matching lines @@
     if (unaliased is ResolutionTypedefType) throw 'unable to unalias $type';
     unaliased.accept(this, builder);
   }
 
   void visitDynamicType(ResolutionDynamicType type, GraphBuilder builder) {
     JavaScriptBackend backend = builder.compiler.backend;
     ClassElement cls = backend.helpers.DynamicRuntimeType;
     builder.push(new HDynamicType(type, new TypeMask.exact(cls, closedWorld)));
   }
 }