Remove Compiler.mainApp and Compiler.mainFunction

tests/compiler/dart2js/parser_helper.dart

 // Copyright (c) 2016, 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 parser_helper;
 
 import 'package:expect/expect.dart';
 
 import 'package:compiler/src/elements/elements.dart';
 import 'package:compiler/src/id_generator.dart';
@@ skipping 19 matching lines @@
 
 import 'options_helper.dart';
 
 export 'package:front_end/src/fasta/parser.dart' hide parse;
 export 'package:front_end/src/fasta/scanner.dart' hide scan;
 export 'package:compiler/src/diagnostics/diagnostic_listener.dart';
 export 'package:compiler/src/parser/node_listener.dart';
 export 'package:compiler/src/parser/diet_parser_task.dart';
 export 'package:front_end/src/fasta/scanner/token_constants.dart';
 
+import 'mock_compiler.dart';
+
 class LoggerCanceler extends DiagnosticReporter {
   DiagnosticOptions get options => const MockDiagnosticOptions();
 
   void log(message) {
     print(message);
   }
 
   void internalError(node, String message) {
     log(message);
   }
@@ skipping 58 matching lines @@
   assert(endToken.kind == EOF_TOKEN);
   Node node = listener.popNode();
   Expect.isNotNull(node);
   Expect.isTrue(listener.nodes.isEmpty, 'Not empty: ${listener.nodes}');
   return node;
 }
 
 Node parseStatement(String text) =>
     parseBodyCode(text, (parser, tokens) => parser.parseStatement(tokens));
 
-Node parseFunction(String text, Compiler compiler) {
+Node parseFunction(String text, MockCompiler compiler) {
   ElementX element = parseUnit(text, compiler, compiler.mainApp).head;
   Expect.isNotNull(element);
   Expect.equals(ElementKind.FUNCTION, element.kind);
   return element.parseNode(compiler.parsingContext);
 }
 
 Node parseMember(String text, {DiagnosticReporter reporter}) {
   return parseBodyCode(text, (parser, tokens) => parser.parseMember(tokens),
       reporter: reporter);
 }
@@ skipping 21 matching lines @@
       new IdGenerator());
   PartialParser parser = new PartialParser(listener);
   reporter.withCurrentElement(unit, () => parser.parseUnit(tokens));
   return unit.localMembers;
 }
 
 NodeList fullParseUnit(String source, {DiagnosticReporter reporter}) {
   return parseBodyCode(source, (parser, tokens) => parser.parseUnit(tokens),
       reporter: reporter);
 }