Refactor BackendHelpers to be reusageable with KernelWorldBuilder

pkg/compiler/lib/src/common/resolution.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.
 
 library dart2js.common.resolution;
 
 import '../common.dart';
 import '../compile_time_constants.dart';
 import '../constants/expressions.dart' show ConstantExpression;
 import '../constants/values.dart' show ConstantValue;
@@ skipping 195 matching lines @@
   /// impact.
   void emptyCache();
 
   /// Returns `true` if [value] is the top-level [proxy] annotation from the
   /// core library.
   bool isProxyConstant(ConstantValue value);
 }
 
 /// A container of commonly used dependencies for tasks that involve parsing.
 abstract class ParsingContext {
-  factory ParsingContext(DiagnosticReporter reporter, ParserTask parser,
-      ScannerTask scanner, PatchParserTask patchParser, Backend backend)
-      = _ParsingContext;
+  factory ParsingContext(
+      DiagnosticReporter reporter,
+      ParserTask parser,
+      ScannerTask scanner,
+      PatchParserTask patchParser,
+      Backend backend) = _ParsingContext;
 
   DiagnosticReporter get reporter;
   ParserTask get parser;
   ScannerTask get scanner;
   PatchParserTask get patchParser;
 
   /// Use [patchParser] directly instead.
   @deprecated
   void parsePatchClass(ClassElement cls);
 
   /// Use [parser] and measure directly instead.
   @deprecated
   measure(f());
 
   /// Get the [ScannerOptions] to scan the given [element].
   ScannerOptions getScannerOptionsFor(Element element);
 }
 
 class _ParsingContext implements ParsingContext {
   final DiagnosticReporter reporter;
   final ParserTask parser;
   final ScannerTask scanner;
   final PatchParserTask patchParser;
   final Backend backend;
 
-  _ParsingContext(this.reporter, this.parser, this.scanner, this.patchParser,
-      this.backend);
+  _ParsingContext(
+      this.reporter, this.parser, this.scanner, this.patchParser, this.backend);
 
   @override
   measure(f()) => parser.measure(f);
 
   @override
   void parsePatchClass(ClassElement cls) {
     patchParser.measure(() {
       if (cls.isPatch) {
         patchParser.parsePatchClassNode(cls);
       }
     });
   }
 
   @override
   ScannerOptions getScannerOptionsFor(Element element) => new ScannerOptions(
       canUseNative: backend.canLibraryUseNative(element.library));
 }