Add operators test to source_mapping_test.

pkg/compiler/lib/src/io/source_information.dart

 // Copyright (c) 2015, 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.source_information;
 
 import '../dart2jslib.dart' show SourceSpan, MessageKind;
 import '../elements/elements.dart' show
     AstElement,
     LocalElement;
@@ skipping 56 matching lines @@
 
   /// Generate [SourceInformation] for the return [node].
   SourceInformation buildReturn(Node node) => null;
 
   /// Generate [SourceInformation] for an implicit return in [element].
   SourceInformation buildImplicitReturn(AstElement element) => null;
 
   /// Generate [SourceInformation] for the loop [node].
   SourceInformation buildLoop(Node node) => null;
 
-  /// Generate [SourceInformation] for the read access in [node].
+  /// Generate [SourceInformation] for a read access like `a.b` where in
+  /// [receiver] points to the left-most part of the access, `a` in the example,
+  /// and [property] points to the 'name' of accessed property, `b` in the
+  /// example.
   SourceInformation buildGet(Node node) => null;
 
-  /// Generate [SourceInformation] for an invocation like `a.b()` where
-  /// [receiver] points to the left-most part of the invocation, `a` in the
-  /// example, and [call] points the 'name' of the call, `b` or `()` depending
-  /// on whether `b` is a method or a field/getter.
+  /// Generate [SourceInformation] for the read access in [node].
   SourceInformation buildCall(Node receiver, Node call) => null;
 
   /// Generate [SourceInformation] for the if statement in [node].
   SourceInformation buildIf(Node node) => null;
 
   /// Generate [SourceInformation] for the constructor invocation in [node].
   SourceInformation buildNew(Node node) => null;
 
   /// Generate [SourceInformation] for the throw in [node].
   SourceInformation buildThrow(Node node) => null;
@@ skipping 94 matching lines @@
     return '${computeElementNameForSourceMaps(local.executableContext)}.$name';
   } else if (element.enclosingClass != null) {
     if (element.enclosingClass.isClosure) {
       return computeElementNameForSourceMaps(element.enclosingClass);
     }
     return '${element.enclosingClass.name}.${element.name}';
   } else {
     return element.name;
   }
 }