Make Map.keys/values Iterables.

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

Index: sdk/lib/_internal/compiler/implementation/native_handler.dart
diff --git a/sdk/lib/_internal/compiler/implementation/native_handler.dart b/sdk/lib/_internal/compiler/implementation/native_handler.dart
index 6e54ac393191c84164820c518fb1ac1624f84cc5..3e83d9f5106701500b507eeaca2ecc8f331498c8 100644
--- a/sdk/lib/_internal/compiler/implementation/native_handler.dart
+++ b/sdk/lib/_internal/compiler/implementation/native_handler.dart
@@ -33,7 +33,7 @@ class SpecialType {
  */
 class NativeEnqueuer {
   /// Initial entry point to native enqueuer.
-  void processNativeClasses(Collection<LibraryElement> libraries) {}
+  void processNativeClasses(Iterable<LibraryElement> libraries) {}
   void processNativeClassesInLibrary(LibraryElement library) {}
 
   /// Notification of a main Enqueuer worklist element.  For methods, adds
@@ -102,7 +102,7 @@ abstract class NativeEnqueuerBase implements NativeEnqueuer {
   /// Subclasses of [NativeEnqueuerBase] are constructed by the backend.
   NativeEnqueuerBase(this.world, this.compiler, this.enableLiveTypeAnalysis);
 
-  void processNativeClasses(Collection<LibraryElement> libraries) {
+  void processNativeClasses(Iterable<LibraryElement> libraries) {
     libraries.forEach(processNativeClassesInLibrary);
     if (!enableLiveTypeAnalysis) {
       nativeClasses.forEach((c) => enqueueClass(c, 'forced'));
@@ -400,7 +400,7 @@ class NativeCodegenEnqueuer extends NativeEnqueuerBase {
   NativeCodegenEnqueuer(Enqueuer world, Compiler compiler, this.emitter)
     : super(world, compiler, compiler.enableNativeLiveTypeAnalysis);
 
-  void processNativeClasses(Collection<LibraryElement> libraries) {
+  void processNativeClasses(Iterable<LibraryElement> libraries) {
     super.processNativeClasses(libraries);
 
     // HACK HACK - add all the resolved classes.