dart2js: Introduce HGetLength to replace strange use of HFieldGet

pkg/compiler/lib/src/ssa/builder_kernel.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.
 
 import 'package:kernel/ast.dart' as ir;
 
 import '../closure.dart';
 import '../common.dart';
 import '../common/codegen.dart' show CodegenRegistry, CodegenWorkItem;
 import '../common/names.dart';
@@ skipping 736 matching lines @@
   ///    }
   _buildForInIndexable(ir.ForInStatement forInStatement) {
     SyntheticLocal indexVariable = new SyntheticLocal('_i', targetElement);
 
     // These variables are shared by initializer, condition, body and update.
     HInstruction array; // Set in buildInitializer.
     bool isFixed; // Set in buildInitializer.
     HInstruction originalLength = null; // Set for growable lists.
 
     HInstruction buildGetLength() {
-      HFieldGet result = new HFieldGet(
-          astAdapter.jsIndexableLength, array, commonMasks.positiveIntType,
+      HGetLength result = new HGetLength(array, commonMasks.positiveIntType,
           isAssignable: !isFixed);
       add(result);
       return result;
     }
 
     void buildConcurrentModificationErrorCheck() {
       if (originalLength == null) return;
       // The static call checkConcurrentModificationError() is expanded in
       // codegen to:
       //
@@ skipping 1851 matching lines @@
 
   static ir.Class _containingClass(ir.TreeNode node) {
     while (node != null) {
       if (node is ir.Class) return node;
       node = node.parent;
     }
     return null;
   }
 
   HInstruction _buildInvokeSuper(
-       ir.Expression invocation, List<HInstruction> arguments) {
+      ir.Expression invocation, List<HInstruction> arguments) {
     // Invocation is either a method invocation or a property get/set.
     // TODO(efortuna): Common interface?
     // TODO(efortuna): Add source information.
     Selector selector = astAdapter.getSelector(invocation);
     HInstruction receiver = localsHandler.readThis();
     ir.Class surroundingClass = _containingClass(invocation);
 
     List<HInstruction> inputs = <HInstruction>[];
     if (astAdapter.isIntercepted(invocation)) {
       inputs.add(_interceptorFor(receiver));
     }
     inputs.add(receiver);
     inputs.addAll(arguments);
 
-    ir.Member interfaceTarget = invocation is ir.SuperMethodInvocation ?
-        (invocation as ir.SuperMethodInvocation).interfaceTarget :
-        (invocation as ir.SuperPropertyGet).interfaceTarget;
+    ir.Member interfaceTarget = invocation is ir.SuperMethodInvocation
+        ? (invocation as ir.SuperMethodInvocation).interfaceTarget
+        : (invocation as ir.SuperPropertyGet).interfaceTarget;
 
     HInstruction instruction = new HInvokeSuper(
         astAdapter.getMember(interfaceTarget),
         astAdapter.getClass(surroundingClass),
         selector,
         inputs,
         astAdapter.returnTypeOf(interfaceTarget),
         null,
         isSetter: selector.isSetter || selector.isIndexSet);
     instruction.sideEffects =
@@ skipping 449 matching lines @@
     enterBlock.setBlockFlow(
         new HTryBlockInformation(
             kernelBuilder.wrapStatementGraph(bodyGraph),
             exception,
             kernelBuilder.wrapStatementGraph(catchGraph),
             kernelBuilder.wrapStatementGraph(finallyGraph)),
         exitBlock);
     kernelBuilder.inTryStatement = previouslyInTryStatement;
   }
 }