Use prototype inheritance to reduce number of is check properties.

pkg/compiler/lib/src/js_emitter/new_emitter/model_emitter.dart

 // Copyright (c) 2014, 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.new_js_emitter.model_emitter;
 
 import '../../dart2jslib.dart' show Compiler;
 import '../../js/js.dart' as js;
 import '../../js_backend/js_backend.dart' show
     JavaScriptBackend,
@@ skipping 91 matching lines @@
 
     return js.js.statement(
         boilerplate,
         {'deferredInitializer': emitDeferredInitializerGlobal(program.loadMap),
          'holders': emitHolders(fragment.holders),
          'cyclicThrow':
            backend.emitter.staticFunctionAccess(backend.getCyclicThrowHelper()),
          'outputContainsConstantList': program.outputContainsConstantList,
          'embeddedGlobals': emitEmbeddedGlobals(program.loadMap),
          'constants': emitConstants(fragment.constants),
-         'staticNonFinals': emitStaticNonFinalFields(fragment.staticNonFinalFields),
+         'staticNonFinals':
+           emitStaticNonFinalFields(fragment.staticNonFinalFields),
          'nativeBoilerplate': nativeBoilerplate,
+         'operatorIsPrefix': js.string(namer.operatorIsPrefix),
          'eagerClasses': emitEagerClassInitializations(fragment.libraries),
          'main': fragment.main,
          'code': code});
   }
 
   js.Block emitHolders(List<Holder> holders) {
     // The top-level variables for holders must *not* be renamed by the
     // JavaScript pretty printer because a lot of code already uses the
     // non-renamed names. The generated code looks like this:
     //
@@ skipping 360 matching lines @@
         prototype[descriptor[i]] = descriptor[i + 1];
       }
     } else {
       constructor = descriptor[2];
       for (var i = 3; i < descriptor.length; i += 2) {
         prototype[descriptor[i]] = descriptor[i + 1];
       }
     }
     constructor.builtin\$cls = name;  // Needed for RTI.
     constructor.prototype = prototype;
+    prototype[#operatorIsPrefix + name] = constructor;
     prototype.constructor = constructor;
     return constructor;
   }
 
   function compileMixinConstructor(name, prototype, descriptor) {
     // $mixinFormatDescription.
     var mixinName = descriptor[2];
     var mixinHolderIndex = descriptor[3];
     var mixin = holders[mixinHolderIndex][mixinName].ensureResolved();
     var mixinPrototype = mixin.prototype;
@@ skipping 61 matching lines @@
 
   var end = Date.now();
   print('Setup: ' + (end - start) + ' ms.');
 
   #main();  // Start main.
 
 }(Date.now(), #code)
 }""";
 
 }