Use a shared function to represent type substitutions with dynamic.

pkg/compiler/lib/src/js_emitter/old_emitter/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.
 
 part of dart2js.js_emitter;
 
 
 class OldEmitter implements Emitter {
   final Compiler compiler;
   final CodeEmitterTask task;
@@ skipping 904 matching lines @@
             js.statement(r'''#.# = function(list) {
                                      list.immutable$list = Array;
                                      list.fixed$length = Array;
                                      return list;
                                    }''',
                          [namer.isolateName, makeConstListProperty]),
             compiler, monitor: compiler.dumpInfoTask));
     output.add(N);
   }
 
+  void emitFunctionThatReturnsNull(CodeOutput output) {
+    output.addBuffer(
+        jsAst.prettyPrint(
+            js.statement('#.# = function() {}',
+                         [backend.namer.isolateName,
+                          backend.rti.getFunctionThatReturnsNullName]),
+            compiler, monitor: compiler.dumpInfoTask));
+  }
+
+  jsAst.Expression generateFunctionThatReturnsNull() {

[karlklose, 2015/01/20 10:37:32]

This generates code to access the function, not the function itself.

+    return js("#.#", [backend.namer.isolateName,
+                      backend.rti.getFunctionThatReturnsNullName]);
+  }
+
   /// Returns the code equivalent to:
   ///   `function(args) { $.startRootIsolate(X.main$closure(), args); }`
   jsAst.Expression buildIsolateSetupClosure(Element appMain,
                                             Element isolateMain) {
     jsAst.Expression mainAccess = isolateStaticClosureAccess(appMain);
     // Since we pass the closurized version of the main method to
     // the isolate method, we must make sure that it exists.
     return js('function(a){ #(#, a); }',
         [backend.emitter.staticFunctionAccess(isolateMain), mainAccess]);
   }
@@ skipping 517 matching lines @@
     if (isProgramSplit) {
       mainOutput.add(
           '${globalsHolder}.${namer.isolateName}$_=$_${namer.isolateName}$N'
           '${globalsHolder}.$initName$_=${_}$initName$N'
           '${globalsHolder}.$parseReflectionDataName$_=$_'
             '$parseReflectionDataName$N');
     }
     mainOutput.add('init()$N$n');
     mainOutput.add('$isolateProperties$_=$_$isolatePropertiesName$N');
 
+    emitFunctionThatReturnsNull(mainOutput);
+
     emitStaticFunctions(task.outputStaticLists[mainOutputUnit]);
 
     List<ClassElement> classes = task.outputClassLists[mainOutputUnit];
     if (classes != null) {
       for (ClassElement element in classes) {
         generateClass(element, getElementDescriptor(element));
       }
     }
 
     if (compiler.enableMinification) {
@@ skipping 620 matching lines @@
     for (Element element in compiler.enqueuer.codegen.newlyEnqueuedElements) {
       if (element.isInstanceMember) {
         cachedClassBuilders.remove(element.enclosingClass);
 
         nativeEmitter.cachedBuilders.remove(element.enclosingClass);
 
       }
     }
   }
 }