Better bitwise and binary arithmetic when the left operand is known to be a number.

tests/compiler/dart2js/mock_compiler.dart

 // Copyright (c) 2012, 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('mock_compiler');
 
 #import("dart:uri");
 
 #import("../../../lib/compiler/implementation/elements/elements.dart");
 #import("../../../lib/compiler/implementation/leg.dart");
 #import("../../../lib/compiler/implementation/tree/tree.dart");
 #import("../../../lib/compiler/implementation/util/util.dart");
 #import("parser_helper.dart");
 
 class WarningMessage {
   Node node;
   Message message;
   WarningMessage(this.node, this.message);
 
   toString() => message.toString();
 }
 
 final String DEFAULT_HELPERLIB = @'''
   lt() {} add(var a, var b) {} sub() {} mul() {} div() {} tdiv() {} mod() {}
   neg() {} shl() {} shr() {} eq() {} le() {} gt() {} ge() {}
   or() {} and() {} not() {} eqNull(a) {} eqq() {}
   ltB() {} leB() {} eqB() {} gtB() {} geB() {} eqNullB(a) {}
-  iae(x) {throw x;} ioore(x) {throw x;}
+  captureStackTrace(x) { return x; }
+  iae(x) { throw x; } ioore(x) { throw x; }
   guard$array(x) { return x; }
   guard$num(x) { return x; }
   guard$string(x) { return x; }
   guard$stringOrArray(x) { return x; }
   index(a, index) {}
   indexSet(a, index, value) {}
   setRuntimeTypeInfo(a, b) {}
   getRuntimeTypeInfo(a) {}
   interface JavaScriptIndexingBehavior {}
   S() {}''';
@@ skipping 160 matching lines @@
   importLibrary(library, compiler.coreLibrary, compiler);
   return library;
 }
 
 class StringScript extends Script {
   final String code;
   StringScript(this.code) : super(null, null);
   String get text() => code;
   String get name() => "mock script";
 }