Revert "Introduces `ParserOptions`."

pkg/compiler/lib/src/parser/diet_parser_task.dart

Index: pkg/compiler/lib/src/parser/diet_parser_task.dart
diff --git a/pkg/compiler/lib/src/parser/diet_parser_task.dart b/pkg/compiler/lib/src/parser/diet_parser_task.dart
index d2db818f48ffa10dc4a6b5283b88233a8d484465..9afc8d4dcb90e6f532ce029a5d19aaad3aaa18f7 100644
--- a/pkg/compiler/lib/src/parser/diet_parser_task.dart
+++ b/pkg/compiler/lib/src/parser/diet_parser_task.dart
@@ -19,26 +19,28 @@ import 'listener.dart' show
 import 'element_listener.dart' show
     ElementListener,
     ScannerOptions;
-import '../options.dart' show
-    ParserOptions;
 import 'partial_parser.dart' show
     PartialParser;
 
 class DietParserTask extends CompilerTask {
-  final ParserOptions _parserOptions;
+  final bool _enableConditionalDirectives;
 
-  DietParserTask(Compiler compiler, this._parserOptions) : super(compiler);
+  DietParserTask(Compiler compiler, {bool enableConditionalDirectives})
+      : this._enableConditionalDirectives = enableConditionalDirectives,
+        super(compiler);
 
   final String name = 'Diet Parser';
 
   dietParse(CompilationUnitElement compilationUnit, Token tokens) {
     measure(() {
       Function idGenerator = compiler.getNextFreeClassId;
-      ScannerOptions scannerOptions =
-          new ScannerOptions.from(compiler, compilationUnit.library);
+      ScannerOptions scannerOptions = new ScannerOptions(
+          canUseNative: compiler.backend.canLibraryUseNative(
+              compilationUnit.library));
       ElementListener listener = new ElementListener(
           scannerOptions, compiler.reporter, compilationUnit, idGenerator);
-      PartialParser parser = new PartialParser(listener, _parserOptions);
+      PartialParser parser = new PartialParser(
+          listener, enableConditionalDirectives: _enableConditionalDirectives);
       try {
         parser.parseUnit(tokens);
       } on ParserError catch(_) {