Add empty mapping entries for the ranges of generated JavaScript that don't map to any Dart source …

tests/compiler/dart2js/source_mapping_test.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.
 
 #import('dart:uri');
 
 #import("../../../lib/compiler/implementation/leg.dart");
 #import('../../../lib/compiler/implementation/source_file.dart');
 #import("mock_compiler.dart");
 #import('parser_helper.dart');
 
-List compileAll(SourceFile sourceFile) {
+CodeBuffer compileAll(SourceFile sourceFile) {
   MockCompiler compiler = new MockCompiler();
   Uri uri = new Uri.fromComponents(sourceFile.filename);
   compiler.sourceFiles[uri.toString()] = sourceFile;
   compiler.runCompiler(uri);
-  return compiler.backend.emitter.sourceMapBuilder.entries;
+  return compiler.backend.emitter.mainBuffer;
 }
 
 void testSourceMapLocations(String codeWithMarkers) {
   List<int> expectedLocations = new List<int>();
   for (int i = 0; i < codeWithMarkers.length; ++i) {
     if (codeWithMarkers[i] == '@') {
       expectedLocations.add(i - expectedLocations.length);
     }
   }
   String code = codeWithMarkers.replaceAll('@', '');
 
   SourceFile sourceFile = new SourceFile('<test script>', code);
-  List entries = compileAll(sourceFile);
+  CodeBuffer buffer = compileAll(sourceFile);
+
   Set<int> locations = new Set<int>();
-  for (var entry in entries) {
-    if (entry.sourceFile == sourceFile) {
-      locations.add(entry.sourceOffset);
+  buffer.forEachSourceLocation((var element, var token, int offset) {
+    if (element != null &&
+        element.getCompilationUnit().script.file == sourceFile) {
+      locations.add(token.charOffset);
     }
-  }
+  });
 
   for (int i = 0; i < expectedLocations.length; ++i) {
     int expectedLocation = expectedLocations[i];
     if (!locations.contains(expectedLocation)) {
       int originalLocation = expectedLocation + i;
       SourceFile sourceFileWithMarkers = new SourceFile('<test script>',
                                                         codeWithMarkers);
       String message = sourceFileWithMarkers.getLocationMessage(
           'Missing location', originalLocation, originalLocation + 1, true,
           (s) => s);
@@ skipping 50 matching lines @@
   // from problematic location.
   testSourceMapLocations(FUNCTIONS_TEST);
   testSourceMapLocations(RETURN_TEST);
   testSourceMapLocations(NOT_TEST);
   testSourceMapLocations(UNARY_TEST);
   testSourceMapLocations(BINARY_TEST);
   testSourceMapLocations(SEND_TEST);
   testSourceMapLocations(SEND_SET_TEST);
   testSourceMapLocations(LOOP_TEST);
 }