Revert "Fix bad type-inferrence for logical expressions."

sdk/lib/_internal/compiler/implementation/inferrer/inferrer_visitor.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.
 
 library inferrer_visitor;
 
 import '../dart2jslib.dart' hide Selector, TypedSelector;
 import '../dart_types.dart';
 import '../elements/elements.dart';
 import '../tree/tree.dart';
@@ skipping 817 matching lines @@
             narrow(receiverElement, objectType, node);
           }
           if (Elements.isLocal(argumentElement)) {
             narrow(argumentElement, objectType, node);
           }
         }
       }
     }
   }
 
-  /// Stops the accumulation of is-checks.
-  ///
-  /// Nulls the [isChecks] field.
-  ///
-  /// Returns the old value of [accumulateIsChecks].
-  bool stopAccumulatingIsChecks() {
-    bool oldAccumulateIsChecks = accumulateIsChecks;
-    accumulateIsChecks = false;
-    isChecks = null;
-    return oldAccumulateIsChecks;
-  }
-
   T visitOperatorSend(Send node) {
     Operator op = node.selector;
     if ("[]" == op.source) {
       return visitDynamicSend(node);
     } else if ("&&" == op.source) {
       conditionIsSimple = false;
       bool oldAccumulateIsChecks = accumulateIsChecks;
-      if (!accumulateIsChecks) {
-        accumulateIsChecks = true;
-        isChecks = <Send>[];
-      }
+      accumulateIsChecks = true;
+      if (isChecks == null) isChecks = <Send>[];
       visit(node.receiver);
-      if (!oldAccumulateIsChecks) {
-        accumulateIsChecks = false;
-        isChecks = null;
-      }
+      accumulateIsChecks = oldAccumulateIsChecks;
+      if (!accumulateIsChecks) isChecks = null;
       LocalsHandler<T> saved = locals;
       locals = new LocalsHandler<T>.from(locals, node);
       updateIsChecks(isChecks, usePositive: true);
       visit(node.arguments.head);
       saved.mergeDiamondFlow(locals, null);
       locals = saved;
       return types.boolType;
     } else if ("||" == op.source) {
       conditionIsSimple = false;
       List<Send> tests = <Send>[];
-      bool isSimple = handleCondition(node.receiver, tests);
+      handleCondition(node.receiver, tests);
       LocalsHandler<T> saved = locals;
       locals = new LocalsHandler<T>.from(locals, node);
-      if (isSimple) updateIsChecks(tests, usePositive: false);
-      bool oldAccumulateIsChecks = stopAccumulatingIsChecks();
+      updateIsChecks(tests, usePositive: false);
+      bool oldAccumulateIsChecks = accumulateIsChecks;
+      accumulateIsChecks = false;
       visit(node.arguments.head);
       accumulateIsChecks = oldAccumulateIsChecks;
       saved.mergeDiamondFlow(locals, null);
       locals = saved;
       return types.boolType;
     } else if ("!" == op.source) {
-      bool oldAccumulateIsChecks = stopAccumulatingIsChecks();
+      bool oldAccumulateIsChecks = accumulateIsChecks;
+      accumulateIsChecks = false;
       node.visitChildren(this);
       accumulateIsChecks = oldAccumulateIsChecks;
       return types.boolType;
     } else if ("is" == op.source) {
       potentiallyAddIsCheck(node);
       node.visitChildren(this);
       return types.boolType;
     } else if ("as" == op.source) {
       T receiverType = visit(node.receiver);
       DartType type = elements.getType(node.arguments.head);
@@ skipping 322 matching lines @@
     return type;
   }
 
   T visitCascade(Cascade node) {
     // Ignore the result of the cascade send and return the type of the cascade
     // receiver.
     visit(node.expression);
     return cascadeReceiverStack.removeLast();
   }
 }