dart2js: move native boilerplate code into a separate file.

pkg/compiler/lib/src/js_emitter/old_emitter/emitter.dart

Index: pkg/compiler/lib/src/js_emitter/old_emitter/emitter.dart
diff --git a/pkg/compiler/lib/src/js_emitter/old_emitter/emitter.dart b/pkg/compiler/lib/src/js_emitter/old_emitter/emitter.dart
index 1ad8c6382e785678ae8fd44d0fc99e78a38d705e..5121465f30116663caba3272165b82768ab0a4a3 100644
--- a/pkg/compiler/lib/src/js_emitter/old_emitter/emitter.dart
+++ b/pkg/compiler/lib/src/js_emitter/old_emitter/emitter.dart
@@ -927,65 +927,6 @@ class OldEmitter implements Emitter {
         [backend.emitter.staticFunctionAccess(isolateMain), mainAccess]);
   }
 
-  /**
-   * Emits code that sets the `isolateTag embedded global to a unique string.
-   */
-  jsAst.Expression generateIsolateAffinityTagInitialization() {
-    jsAst.Expression getIsolateTagAccess =
-        generateEmbeddedGlobalAccess(embeddedNames.GET_ISOLATE_TAG);
-    jsAst.Expression isolateTagAccess =
-        generateEmbeddedGlobalAccess(embeddedNames.ISOLATE_TAG);
-
-    return js('''
-      !function() {
-        // On V8, the 'intern' function converts a string to a symbol, which
-        // makes property access much faster.
-        function intern(s) {
-          var o = {};
-          o[s] = 1;
-          return Object.keys(convertToFastObject(o))[0];
-        }
-
-        #getIsolateTag = function(name) {
-          return intern("___dart_" + name + #isolateTag);
-        };
-
-        // To ensure that different programs loaded into the same context (page)
-        // use distinct dispatch properies, we place an object on `Object` to
-        // contain the names already in use.
-        var tableProperty = "___dart_isolate_tags_";
-        var usedProperties = Object[tableProperty] ||
-            (Object[tableProperty] = Object.create(null));
-
-        var rootProperty = "_${generateIsolateTagRoot()}";
-        for (var i = 0; ; i++) {
-          var property = intern(rootProperty + "_" + i + "_");
-          if (!(property in usedProperties)) {
-            usedProperties[property] = 1;
-            #isolateTag = property;
-            break;
-          }
-        }
-      }()
-    ''',
-    {'getIsolateTag': getIsolateTagAccess, 'isolateTag': isolateTagAccess});
-  }
-
-  jsAst.Expression generateDispatchPropertyNameInitialization() {
-    jsAst.Expression dispatchPropertyNameAccess =
-        generateEmbeddedGlobalAccess(embeddedNames.DISPATCH_PROPERTY_NAME);
-    jsAst.Expression getIsolateTagAccess =
-        generateEmbeddedGlobalAccess(embeddedNames.GET_ISOLATE_TAG);
-    return js('# = #("dispatch_record")',
-        [dispatchPropertyNameAccess,
-         getIsolateTagAccess]);
-  }
-
-  String generateIsolateTagRoot() {
-    // TODO(sra): MD5 of contributing source code or URIs?
-    return 'ZxYxX';
-  }
-
   emitMain(CodeBuffer buffer) {
     if (compiler.isMockCompilation) return;
     Element main = compiler.mainFunction;
@@ -1002,16 +943,20 @@ class OldEmitter implements Emitter {
       mainCallClosure = backend.emitter.staticFunctionAccess(main);
     }
 
+    NativeGenerator nativeGenerator =
+        new NativeGenerator(generateEmbeddedGlobalAccess);
     if (backend.needToInitializeIsolateAffinityTag) {
       buffer.write(
-          jsAst.prettyPrint(generateIsolateAffinityTagInitialization(),
-                            compiler, monitor: compiler.dumpInfoTask));
+          jsAst.prettyPrint(
+              nativeGenerator.generateIsolateAffinityTagInitialization(),
+              compiler, monitor: compiler.dumpInfoTask));
       buffer.write(N);
     }
     if (backend.needToInitializeDispatchProperty) {
       assert(backend.needToInitializeIsolateAffinityTag);
       buffer.write(
-          jsAst.prettyPrint(generateDispatchPropertyNameInitialization(),
+          jsAst.prettyPrint(
+              nativeGenerator.generateDispatchPropertyNameInitialization(),
               compiler, monitor: compiler.dumpInfoTask));
       buffer.write(N);
     }