fix warnings/test failures due to analyzer warnings, update stauts to include

pkg/compiler/lib/src/cps_ir/cps_ir_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.
 
 library dart2js.ir_builder;
 
 import '../closure.dart' as closure;
 import '../common.dart';
 import '../common/names.dart' show
     Names,
     Selectors;
 import '../compile_time_constants.dart' show
     BackendConstantEnvironment;
 import '../constants/constant_system.dart';
 import '../constants/values.dart' show
     ConstantValue,
     PrimitiveConstantValue;
 import '../dart_types.dart';
 import '../elements/elements.dart';
 import '../io/source_information.dart';
 import '../js/js.dart' as js show
     js,
     objectLiteral,
+    Expression,
     LiteralStatement,
     Template,
     InterpolatedExpression,
     isIdentityTemplate;
 import '../native/native.dart' show
     NativeBehavior;
 import '../tree/tree.dart' as ast;
 import '../types/types.dart' show
     TypeMask;
 import '../universe/call_structure.dart' show
@@ skipping 2031 matching lines @@
     // its value.
     ir.Primitive value = buildForeignCode(
         js.js.uncachedExpressionTemplate(code),
         arguments,
         behavior,
         type: program.getTypeMaskForNativeFunction(function));
     buildReturn(value: value, sourceInformation: source);
   }
 
   static _isNotNull(ir.Primitive value) =>
-      value is! ir.Constant || !value.value.isNull;
+      !(value is ir.Constant && value.value.isNull);
 
   /// Builds a call to a resolved js-interop element.
   ir.Primitive buildInvokeJsInteropMember(FunctionElement element,
       List<ir.Primitive> arguments) {
     program.addNativeMethod(element);
     String target = program.getJsInteropTargetPath(element);
     // Strip off trailing arguments that were not specified.
     // TODO(jacobr,sigmund): assert that the trailing arguments are all null.
     // TODO(jacobr): rewrite named arguments to an object literal matching
     // the factory constructor case.
@@ skipping 849 matching lines @@
                    this.stackTraceVariable,
                    this.buildCatchBlock});
 }
 
 class SwitchCaseInfo {
   final SubbuildFunction buildCondition;
   final SubbuildFunction buildBody;
 
   SwitchCaseInfo(this.buildCondition, this.buildBody);
 }