Extract BackendUsage, MirrorsData, and CheckedModeHelpers from Backend.

pkg/compiler/lib/src/js_emitter/full_emitter/setup_program_builder.dart

 // Copyright (c) 2013, 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.
 
 part of dart2js.js_emitter.full_emitter;
 
 // TODO(ahe): Share these with js_helper.dart.
 const FUNCTION_INDEX = 0;
 const NAME_INDEX = 1;
 const CALL_NAME_INDEX = 2;
@@ skipping 54 matching lines @@
   jsAst.Expression instanceFromClassIdAccess = emitter
       .generateEmbeddedGlobalAccess(embeddedNames.INSTANCE_FROM_CLASS_ID);
 
   String reflectableField = namer.reflectableField;
   String reflectionInfoField = namer.reflectionInfoField;
   String reflectionNameField = namer.reflectionNameField;
   String metadataIndexField = namer.metadataIndexField;
   String defaultValuesField = namer.defaultValuesField;
   String methodsWithOptionalArgumentsField =
       namer.methodsWithOptionalArgumentsField;
-  String unmangledNameIndex = backend.mustRetainMetadata
+  String unmangledNameIndex = backend.mirrorsData.mustRetainMetadata
       ? ' 3 * optionalParameterCount + 2 * requiredParameterCount + 3'
       : ' 2 * optionalParameterCount + requiredParameterCount + 3';
   String receiverParamName =
       compiler.options.enableMinification ? "r" : "receiver";
   String valueParamName = compiler.options.enableMinification ? "v" : "value";
   String space = compiler.options.enableMinification ? "" : " ";
   String _ = space;
 
   String specProperty = '"${namer.nativeSpecProperty}"'; // "%"
   jsAst.Expression nativeInfoAccess = js('prototype[$specProperty]', []);
@@ skipping 26 matching lines @@
     'hasIsolateSupport': program.hasIsolateSupport,
     'fieldNamesProperty': js.string(Emitter.FIELD_NAMES_PROPERTY_NAME),
     'createNewIsolateFunction': createNewIsolateFunctionAccess,
     'isolateName': namer.isolateName,
     'classIdExtractor': classIdExtractorAccess,
     'classFieldsExtractor': classFieldsExtractorAccess,
     'instanceFromClassId': instanceFromClassIdAccess,
     'initializeEmptyInstance': initializeEmptyInstanceAccess,
     'allClasses': allClassesAccess,
     'debugFastObjects': DEBUG_FAST_OBJECTS,
-    'isTreeShakingDisabled': backend.isTreeShakingDisabled,
+    'isTreeShakingDisabled': backend.mirrorsData.isTreeShakingDisabled,
     'precompiled': precompiledAccess,
     'finishedClassesAccess': finishedClassesAccess,
     'needsMixinSupport': emitter.needsMixinSupport,
     'needsNativeSupport': program.needsNativeSupport,
     'enabledJsInterop': backend.jsInteropAnalysis.enabledJsInterop,
     'jsInteropBoostrap': backend.jsInteropAnalysis.buildJsInteropBootstrap(),
     'isInterceptorClass': namer.operatorIs(backend.helpers.jsInterceptorClass),
     'isObject': namer.operatorIs(compiler.commonElements.objectClass),
     'specProperty': js.string(namer.nativeSpecProperty),
     'trivialNsmHandlers': emitter.buildTrivialNsmHandlers(),
-    'hasRetainedMetadata': backend.hasRetainedMetadata,
+    'hasRetainedMetadata': backend.mirrorsData.hasRetainedMetadata,
     'types': typesAccess,
     'objectClassName': js.quoteName(
         namer.runtimeTypeName(compiler.commonElements.objectClass as Entity)),
     'needsStructuredMemberInfo': emitter.needsStructuredMemberInfo,
     'usesMangledNames': compiler.commonElements.mirrorsLibrary != null ||
         backend.hasFunctionApplySupport,
     'tearOffCode': buildTearOffCode(backend),
     'nativeInfoHandler': nativeInfoHandler,
     'operatorIsPrefix': js.string(namer.operatorIsPrefix),
     'deferredActionString': js.string(namer.deferredAction)
@@ skipping 697 matching lines @@
 (function() {
   var result = $array[$index];
   if ($check) {
     throw new Error(
         name + ": expected value of type \'$type\' at index " + ($index) +
         " but got " + (typeof result));
   }
   return result;
 })()''';
 }