Fix shift in source map positions.

tests/compiler/dart2js/source_map_deferred_d2js_validity_test.dart

Index: tests/compiler/dart2js/source_map_deferred_d2js_validity_test.dart
diff --git a/tests/compiler/dart2js/source_map_deferred_d2js_validity_test.dart b/tests/compiler/dart2js/source_map_deferred_d2js_validity_test.dart
index 83a1f8295390506c263e5b6e1397600bd3248766..19c8f711411f2c94cacf49a119333e9178309300 100644
--- a/tests/compiler/dart2js/source_map_deferred_d2js_validity_test.dart
+++ b/tests/compiler/dart2js/source_map_deferred_d2js_validity_test.dart
@@ -27,8 +27,12 @@ void main() {
                                    windows: Platform.isWindows);
         Uri deferredUri = new Uri.file('${tmpDir.path}/out.js_1.part.js',
                                        windows: Platform.isWindows);
-        validateSourceMap(mainUri, compiler);
-        validateSourceMap(deferredUri, compiler);
+        validateSourceMap(mainUri,
+                          mainUri: Uri.base.resolve(file),
+                          mainPosition: const Position(7, 1),
+                          compiler: compiler);
+        validateSourceMap(deferredUri,
+                          compiler: compiler);
 
         print("Deleting '${tmpDir.path}'.");
         tmpDir.deleteSync(recursive: true);