[kernel] offsets on direct property get/set

pkg/front_end/lib/src/fasta/kernel/frontend_accessors.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.
 
 // Note: copied from package:kernel at revision 7346348.
 
 /// A library to help transform compounds and null-aware accessors into
 /// let expressions.
 library kernel.frontend.accessors;
 
@@ skipping 207 matching lines @@
 
   _finish(Expression body) => makeLet(
       receiver,
       new ConditionalExpression(
           buildIsNull(receiverAccess()), new NullLiteral(), body, type));
 }
 
 class SuperPropertyAccessor extends Accessor {
   Name name;
   Member getter, setter;
+  final int charOffset;
 
-  SuperPropertyAccessor(this.name, this.getter, this.setter);
+  SuperPropertyAccessor(this.name, this.getter, this.setter, this.charOffset);
 
   _makeRead() {
     if (getter == null) return makeInvalidRead();
     // TODO(ahe): Use [DirectPropertyGet] when possible.
-    Expression result = new DirectPropertyGet(new ThisExpression(), getter);
-    result = new SuperPropertyGet(name, getter);
+    Expression result = new DirectPropertyGet(new ThisExpression(), getter)
+      ..fileOffset = charOffset;
+    result = new SuperPropertyGet(name, getter)..fileOffset = charOffset;
     return result;
   }
 
   _makeWrite(Expression value, bool voidContext) {
     if (setter == null) return makeInvalidWrite(value);
     // TODO(ahe): Use [DirectPropertySet] when possible.
-    Expression result =
-        new DirectPropertySet(new ThisExpression(), setter, value);
-    result = new SuperPropertySet(name, value, setter);
+    Expression result = new DirectPropertySet(
+        new ThisExpression(), setter, value)..fileOffset = charOffset;
+    result = new SuperPropertySet(name, value, setter)..fileOffset = charOffset;
     return result;
   }
 }
 
 final Name _indexGet = new Name('[]');
 final Name _indexSet = new Name('[]=');
 
 class IndexAccessor extends Accessor {
   Expression receiver;
   Expression index;
@@ skipping 228 matching lines @@
 
 VariableDeclaration makeOrReuseVariable(Expression value) {
   // TODO: Devise a way to remember if a variable declaration was reused
   // or is fresh (hence needs a let binding).
   return new VariableDeclaration.forValue(value);
 }
 
 Expression wrapInvalid(Expression e) {
   return new Let(new VariableDeclaration.forValue(e), new InvalidExpression());
 }