Use prototype inheritance to reduce number of is check properties.

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

Index: pkg/compiler/lib/src/js_emitter/new_emitter/model_emitter.dart
diff --git a/pkg/compiler/lib/src/js_emitter/new_emitter/model_emitter.dart b/pkg/compiler/lib/src/js_emitter/new_emitter/model_emitter.dart
index a2b1c62fac1067953f7190305ed5066e56196c76..1c8b0b98fc58da16152a30f52635ca430355e401 100644
--- a/pkg/compiler/lib/src/js_emitter/new_emitter/model_emitter.dart
+++ b/pkg/compiler/lib/src/js_emitter/new_emitter/model_emitter.dart
@@ -109,8 +109,10 @@ class ModelEmitter {
          '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});
@@ -491,6 +493,7 @@ class ModelEmitter {
     }
     constructor.builtin\$cls = name;  // Needed for RTI.
     constructor.prototype = prototype;
+    prototype[#operatorIsPrefix + name] = constructor;
     prototype.constructor = constructor;
     return constructor;
   }