Do not allow native syntax on all libraries.

dart/frog/leg/compiler.dart

Index: dart/frog/leg/compiler.dart
===================================================================
--- dart/frog/leg/compiler.dart	(revision 4858)
+++ dart/frog/leg/compiler.dart	(working copy)
@@ -74,6 +74,7 @@
   SsaCodeGeneratorTask generator;
   CodeEmitterTask emitter;
   CompileTimeConstantHandler compileTimeConstantHandler;
+  native.NativeHandler nativeHandler;
 
   static final SourceString MAIN = const SourceString('main');
   static final SourceString NO_SUCH_METHOD = const SourceString('noSuchMethod');
@@ -96,9 +97,10 @@
     optimizer = new SsaOptimizerTask(this);
     generator = new SsaCodeGeneratorTask(this);
     emitter = new CodeEmitterTask(this);
+    nativeHandler = new native.NativeHandler(this);
     tasks = [scanner, dietParser, parser, resolver, checker,
              builder, optimizer, generator,
-             emitter, compileTimeConstantHandler];
+             emitter, compileTimeConstantHandler, nativeHandler];
   }
 
   void ensure(bool condition) {
@@ -251,7 +253,7 @@
   void runCompiler(Script script) {
     scanBuiltinLibraries();
     mainApp = new LibraryElement(script);
-    native.checkNativeSupport(this, mainApp, null);
+    nativeHandler.checkNativeSupport(mainApp, null);
 
     Element element;
     withCurrentElement(mainApp, () {