Remove BackendClasses and JavaScriptBackendClasses.

pkg/compiler/lib/src/ssa/invoke_dynamic_specializers.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.
 
 import '../common_elements.dart' show CommonElements;
 import '../constants/constant_system.dart';
 import '../constants/values.dart';
 import '../elements/elements.dart' show Name;
 import '../elements/entities.dart';
 import '../options.dart';
@@ skipping 918 matching lines @@
     TypeMask instructionType = left.instructionType;
     if (right.isConstantNull() || left.isPrimitiveOrNull(closedWorld)) {
       return newBuiltinVariant(instruction, closedWorld);
     }
     Iterable<MemberEntity> matches =
         closedWorld.allFunctions.filter(instruction.selector, instructionType);
     // This test relies the on `Object.==` and `Interceptor.==` always being
     // implemented because if the selector matches by subtype, it still will be
     // a regular object or an interceptor.
     if (matches
-        .every(closedWorld.backendClasses.isDefaultEqualityImplementation)) {
+        .every(closedWorld.commonElements.isDefaultEqualityImplementation)) {
       return newBuiltinVariant(instruction, closedWorld);
     }
     return null;
   }
 
   BinaryOperation operation(ConstantSystem constantSystem) {
     return constantSystem.equal;
   }
 
   HInstruction newBuiltinVariant(
@@ skipping 186 matching lines @@
       ClosedWorld closedWorld) {
     HInstruction receiver = instruction.getDartReceiver(closedWorld);
     if (receiver.isNumberOrNull(closedWorld)) {
       // Even if there is no builtin equivalent instruction, we know the
       // instruction does not have any side effect, and that it can be GVN'ed.
       clearAllSideEffects(instruction);
     }
     return null;
   }
 }