Various caches for incremental compilation.

dart/sdk/lib/_internal/compiler/implementation/native_handler.dart

Index: dart/sdk/lib/_internal/compiler/implementation/native_handler.dart
diff --git a/dart/sdk/lib/_internal/compiler/implementation/native_handler.dart b/dart/sdk/lib/_internal/compiler/implementation/native_handler.dart
index f53d34846da48259480446a986da66d29ce0e4ef..08be6035b252dc8d27182e3fcbb4928164bf6c84 100644
--- a/dart/sdk/lib/_internal/compiler/implementation/native_handler.dart
+++ b/dart/sdk/lib/_internal/compiler/implementation/native_handler.dart
@@ -90,6 +90,9 @@ abstract class NativeEnqueuerBase implements NativeEnqueuer {
   final Set<ClassElement> pendingClasses = new Set<ClassElement>();
   final Set<ClassElement> unusedClasses = new Set<ClassElement>();
 
+  final Set<LibraryElement> processedLibraries =
+      new Set<LibraryElement>.identity();
+
   bool hasInstantiatedNativeClasses() => !registeredClasses.isEmpty;
 
   final Set<ClassElement> nativeClassesAndSubclasses = new Set<ClassElement>();
@@ -124,6 +127,9 @@ abstract class NativeEnqueuerBase implements NativeEnqueuer {
   NativeEnqueuerBase(this.world, this.compiler, this.enableLiveTypeAnalysis);
 
   void processNativeClasses(Iterable<LibraryElement> libraries) {
+    if (compiler.hasIncrementalSupport) {
+      libraries = libraries.where((library) => processedLibraries.add(library));

[floitsch, 2014/06/19 12:00:24]

where(processedLibraries.add)

It's ok without, but I would remind the reader what `add` returns.

[ahe, 2014/06/19 13:50:10]

Done.
Agreed.

+    }
     libraries.forEach(processNativeClassesInLibrary);
     if (compiler.isolateHelperLibrary != null) {
       processNativeClassesInLibrary(compiler.isolateHelperLibrary);