Further reduce use of Element in codegen.

pkg/compiler/lib/src/js_backend/backend_helpers.dart

 // Copyright (c) 2015, 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.js_backend.helpers;
 
 import '../common.dart';
 import '../common/names.dart' show Identifiers, Uris;
 import '../common/resolution.dart' show Resolution;
 import '../compiler.dart' show Compiler;
@@ skipping 483 matching lines @@
   }
 
   MethodElement get _consoleTraceHelper {
     return _findHelper('consoleTraceHelper');
   }
 
   MethodElement get _postTraceHelper {
     return _findHelper('postTraceHelper');
   }
 
-  FunctionElement get closureFromTearOff {
+  MethodElement get closureFromTearOff {
     return _findHelper('closureFromTearOff');
   }
 
   Element get isJsIndexable {
     return _findHelper('isJsIndexable');
   }
 
-  Element get throwIllegalArgumentException {
+  MethodElement get throwIllegalArgumentException {
     return _findHelper('iae');
   }
 
-  Element get throwIndexOutOfRangeException {
+  MethodElement get throwIndexOutOfRangeException {
     return _findHelper('ioore');
   }
 
   Element get exceptionUnwrapper {
     return _findHelper('unwrapException');
   }
 
   Element get throwRuntimeError {
     return _findHelper('throwRuntimeError');
   }
 
   Element get throwTypeError {
     return _findHelper('throwTypeError');
   }
 
   Element get throwAbstractClassInstantiationError {
     return _findHelper('throwAbstractClassInstantiationError');
   }
 
   Element get checkConcurrentModificationError {
     if (cachedCheckConcurrentModificationError == null) {
       cachedCheckConcurrentModificationError =
           _findHelper('checkConcurrentModificationError');
     }
     return cachedCheckConcurrentModificationError;
   }
 
-  Element get throwConcurrentModificationError {
+  MethodElement get throwConcurrentModificationError {
     return _findHelper('throwConcurrentModificationError');
   }
 
   Element get checkInt => _checkInt ??= _findHelper('checkInt');
   Element _checkInt;
 
   Element get checkNum => _checkNum ??= _findHelper('checkNum');
   Element _checkNum;
 
   Element get checkString => _checkString ??= _findHelper('checkString');
   Element _checkString;
 
-  Element get stringInterpolationHelper {
+  MethodElement get stringInterpolationHelper {
     return _findHelper('S');
   }
 
-  Element get wrapExceptionHelper {
+  MethodElement get wrapExceptionHelper {
     return _findHelper(r'wrapException');
   }
 
-  Element get throwExpressionHelper {
+  MethodElement get throwExpressionHelper {
     return _findHelper('throwExpression');
   }
 
   Element get closureConverter {
     return _findHelper('convertDartClosureToJS');
   }
 
   Element get traceFromException {
     return _findHelper('getTraceFromException');
   }
 
   Element get setRuntimeTypeInfo {
     return _findHelper('setRuntimeTypeInfo');
   }
 
   Element get getRuntimeTypeInfo {
     return _findHelper('getRuntimeTypeInfo');
   }
 
-  Element get getTypeArgumentByIndex {
+  MethodElement get getTypeArgumentByIndex {
     return _findHelper('getTypeArgumentByIndex');
   }
 
   Element get computeSignature {
     return _findHelper('computeSignature');
   }
 
   Element get getRuntimeTypeArguments {
     return _findHelper('getRuntimeTypeArguments');
   }
 
-  Element get getRuntimeTypeArgument {
+  MethodElement get getRuntimeTypeArgument {
     return _findHelper('getRuntimeTypeArgument');
   }
 
   Element get runtimeTypeToString {
     return _findHelper('runtimeTypeToString');
   }
 
   Element get assertIsSubtype {
     return _findHelper('assertIsSubtype');
   }
@@ skipping 211 matching lines @@
   }
 
   Element get callInIsolate {
     return _find(isolateHelperLibrary, '_callInIsolate');
   }
 
   Element get findIndexForNativeSubclassType {
     return _findInterceptor('findIndexForNativeSubclassType');
   }
 
-  Element get convertRtiToRuntimeType {
+  MethodElement get convertRtiToRuntimeType {
     return _findHelper('convertRtiToRuntimeType');
   }
 
   ClassElement get stackTraceClass {
     return _findHelper('_StackTrace');
   }
 
   MethodElement _objectNoSuchMethod;
 
   MethodElement get objectNoSuchMethod {
@@ skipping 26 matching lines @@
   }
 
   MethodElement get toStringForNativeObject {
     return _findHelper('toStringForNativeObject');
   }
 
   MethodElement get hashCodeForNativeObject {
     return _findHelper('hashCodeForNativeObject');
   }
 }