Backout earlier change to task model

pkg/analyzer/lib/src/task/dart.dart

 // Copyright (c) 2015, 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.
 
 library analyzer.src.task.dart;
 
 import 'dart:collection';
 
 import 'package:analyzer/src/context/cache.dart';
 import 'package:analyzer/src/generated/ast.dart';
@@ skipping 1594 matching lines @@
     outputs[CONSTANT_DEPENDENCIES] = dependencies;
   }
 
   /**
    * Return a map from the names of the inputs of this kind of task to the task
    * input descriptors describing those inputs for a task with the
    * given [target].
    */
   static Map<String, TaskInput> buildInputs(AnalysisTarget target) {
     //
-    // We need to force the computation of the RESOLVED_UNIT9 for each unit
-    // reachable from the target's library so that all of the AST's for the
-    // constructor initializers that we might encounter have been copied into
-    // the element model.
-    //
-    // TODO(brianwilkerson) This could be improved by computing a more accurate
-    // list of the sources containing constructors that are actually referenced.
+    // TODO(brianwilkerson) I believe that this does not properly guarantee that
+    // all of the constructor initializers that we might encounter have been
+    // copied into the element model. We tried forcing the computation of the
+    // RESOLVED_UNIT9 for each unit reachable from the target's library, but
+    // that had too big a performance impact. We could potentially mitigate the
+    // impact by computing a more accurate list of the sources containing
+    // constructors that are actually referenced, but other approaches should
+    // be considered.
     //
     Source librarySource;
     if (target is Element) {
       CompilationUnitElementImpl unit = target
           .getAncestor((Element element) => element is CompilationUnitElement);
       librarySource = unit.librarySource;
     } else if (target is ConstantEvaluationTarget_Annotation) {
       librarySource = target.librarySource;
     } else {
       throw new AnalysisException(
           'Cannot build inputs for a ${target.runtimeType}');
     }
     return <String, TaskInput>{
-      'resolvedUnits': IMPORT_EXPORT_SOURCE_CLOSURE
-          .of(librarySource)
-          .toFlattenListOf(LIBRARY_SPECIFIC_UNITS)
-          .toListOf(RESOLVED_UNIT9),
+      'resolvedUnit': RESOLVED_UNIT9
+          .of(new LibrarySpecificUnit(librarySource, target.source)),
       TYPE_PROVIDER_INPUT: TYPE_PROVIDER.of(AnalysisContextTarget.request)
     };
   }
 
   /**
    * Create a [ComputeConstantDependenciesTask] based on the given [target] in
    * the given [context].
    */
   static ComputeConstantDependenciesTask createTask(
       AnalysisContext context, AnalysisTarget target) {
@@ skipping 2944 matching lines @@
 
   @override
   bool moveNext() {
     if (_newSources.isEmpty) {
       return false;
     }
     currentTarget = _newSources.removeLast();
     return true;
   }
 }