Element model cleanup + prepare for easier reimplementation.

pkg/compiler/lib/src/use_unused_api.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.
 
 /// This file use methods that aren't used by dart2js.dart, but that we wish to
 /// keep anyway. This might be general API that isn't currently in use,
 /// debugging aids, or API only used for testing (see TODO below).
 
 library dart2js.use_unused_api;
 
@@ skipping 50 matching lines @@
   useJsNode(new js.NamedFunction(null, null));
   useJsNode(new js.ArrayHole());
   useJsOther(new js.SimpleJavaScriptPrintingContext());
   useJsBackend(null);
   useConcreteTypesInferrer(null);
   useColor();
   useFilenames();
   useSsa(null);
   useIo(null, null);
   usedByTests();
-  useElements(null, null, null, null, null);
+  useElements();
   useIr(null, null);
   useCompiler(null);
   useTypes();
   useCodeEmitterTask(null);
   useScript(null);
   useProgramBuilder(null);
   useSemanticVisitor();
   useTreeVisitors();
 }
 
@@ skipping 156 matching lines @@
   typeGraphInferrer.getCallersOf(null);
   dart_types.Types.sorted(null);
   new dart_types.Types(compiler).copy(compiler);
   new universe.TypedSelector.subclass(null, null, compiler.world);
   new universe.TypedSelector.subtype(null, null, compiler.world);
   new universe.TypedSelector.exact(null, null, compiler.world);
   sourceFileProvider.readStringFromUri(null);
 }
 
 useElements(
-    elements.ClassElement e,
-    elements.Name n,
-    modelx.FieldElementX f,
-    PartialClassElement pce,
-    PartialFunctionElement pfe) {
+    [elements.ClassElement e,
+     elements.Name n,
+     modelx.FieldElementX f,
+     PartialClassElement pce,
+     PartialFunctionElement pfe,
+     elements.LibraryElement l]) {
   e.lookupClassMember(null);
   e.lookupInterfaceMember(null);
   n.isAccessibleFrom(null);
   f.reuseElement();
   pce.copyWithEnclosing(null);
   pfe.copyWithEnclosing(null);
+  l.forEachImport(null);
 }
 
 useIr(ir_builder.IrBuilderTask task,
       ir_builder.IrBuilder builder) {
   task
     ..hasIr(null)
     ..getIr(null);
   builder
     ..buildStringConstant(null)
     ..buildDynamicGet(null, null);
@@ skipping 39 matching lines @@
   visitFieldDefinition(tree_ir.FieldDefinition node) {}
 
   visitFieldInitializer(tree_ir.FieldInitializer node) {}
   visitSuperInitializer(tree_ir.SuperInitializer node) {}
 }
 
 useTreeVisitors() {
   new DummyTreeVisitor().visitRootNode(null);
   new DummyTreeVisitor().visitInitializer(null);
 }