Create and test source mapping for invocations.

pkg/compiler/lib/src/js/js_source_mapping.dart

Index: pkg/compiler/lib/src/js/js_source_mapping.dart
diff --git a/pkg/compiler/lib/src/js/js_source_mapping.dart b/pkg/compiler/lib/src/js/js_source_mapping.dart
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+// 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 js.source_mapping;
+
+import 'js.dart';
+import '../io/code_output.dart' show SourceLocations;
+import '../io/source_information.dart' show
+    SourceLocation,
+    SourceInformation,
+    SourceInformationStrategy;
+
+/// [SourceInformationStrategy] that can associate source information with
+/// JavaScript output.
+class JavaScriptSourceInformationStrategy
+    extends SourceInformationStrategy {
+  const JavaScriptSourceInformationStrategy();
+
+  /// Creates a processor that can associate source information on [Node] with
+  /// code offsets in the [sourceMapper].
+  SourceInformationProcessor createProcessor(SourceMapper sourceMapper) {
+    return const SourceInformationProcessor();
+  }
+}
+
+/// An observer of code positions of printed JavaScript [Node]s.
+class CodePositionListener {
+  const CodePositionListener();
+
+  /// Called to associate [node] with the provided start, end and closing
+  /// positions.
+  void onPositions(
+      Node node,
+      int startPosition,
+      int endPosition,
+      int closingPosition) {}
+}
+
+/// An interface for mapping code offsets with [SourceLocation]s for JavaScript
+/// [Node]s.
+abstract class SourceMapper {
+  /// Associate [codeOffset] with [sourceLocation] for [node].
+  void register(Node node, int codeOffset, SourceLocation sourceLocation);
+}
+
+/// An implementation of [SourceMapper] that stores the information directly
+/// into a [SourceLocations] object.
+class SourceLocationsMapper implements SourceMapper {
+  final SourceLocations sourceLocations;
+
+  SourceLocationsMapper(this.sourceLocations);
+
+  @override
+  void register(Node node, int codeOffset, SourceLocation sourceLocation) {
+    sourceLocations.addSourceLocation(codeOffset, sourceLocation);
+  }
+}
+
+/// A processor that associates [SourceInformation] with code position of
+/// JavaScript [Node]s.
+class SourceInformationProcessor extends CodePositionListener {
+  const SourceInformationProcessor();
+
+  /// Process the source information and code positions for the [node] and all
+  /// its children.
+  void process(Node node) {}
+}