Compute an incremental patch to JavaScript code.

dart/sdk/lib/_internal/compiler/implementation/enqueue.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.
 
 part of dart2js;
 
 typedef ItemCompilationContext ItemCompilationContextCreator();
 
 class EnqueueTask extends CompilerTask {
   final ResolutionEnqueuer resolution;
@@ skipping 839 matching lines @@
    *
    * For code generation, we rely on the precomputed set of elements that takes
    * subtyping constraints into account.
    */
   bool shouldIncludeElementDueToMirrors(Element element,
                                         {bool includedEnclosing}) {
     return compiler.backend.isAccessibleByReflection(element);
   }
 
   bool internalAddToWorkList(Element element) {
-    if (compiler.hasIncrementalSupport) {
-      newlyEnqueuedElements.add(element);
-    }
     // Don't generate code for foreign elements.
     if (element.isForeign(compiler.backend)) return false;
 
     // Codegen inlines field initializers. It only needs to generate
     // code for checked setters.
     if (element.isField && element.isInstanceMember) {
       if (!compiler.enableTypeAssertions
           || element.enclosingElement.isClosure) {
         return false;
       }
     }
 
+    if (compiler.hasIncrementalSupport && !isProcessed(element)) {
+      newlyEnqueuedElements.add(element);
+    }
+
     if (queueIsClosed) {
       throw new SpannableAssertionFailure(element,
           "Codegen work list is closed. Trying to add $element");
     }
     CodegenWorkItem workItem = new CodegenWorkItem(
         element, itemCompilationContextCreator());
     queue.add(workItem);
     return true;
   }
 
@@ skipping 33 matching lines @@
   void processWorkItem(void f(WorkItem work), WorkItem work) {
     f(work);
   }
 }
 
 void removeFromSet(Map<String, Set<Element>> map, Element element) {
   Set<Element> set = map[element.name];
   if (set == null) return;
   set.remove(element);
 }