Revert "Compute frontend/backend specific constants."

sdk/lib/_internal/compiler/implementation/dart_backend/backend.dart

Index: sdk/lib/_internal/compiler/implementation/dart_backend/backend.dart
diff --git a/sdk/lib/_internal/compiler/implementation/dart_backend/backend.dart b/sdk/lib/_internal/compiler/implementation/dart_backend/backend.dart
index 94bdc2daa7e5f7517660533dd3baf1e525d62df2..fdd9050f60c1a6978796d02fbd4160bbd335da95 100644
--- a/sdk/lib/_internal/compiler/implementation/dart_backend/backend.dart
+++ b/sdk/lib/_internal/compiler/implementation/dart_backend/backend.dart
@@ -45,14 +45,6 @@ class DartBackend extends Backend {
   Map<Element, TreeElements> get resolvedElements =>
       compiler.enqueuer.resolution.resolvedElements;
 
-  ConstantSystem get constantSystem {
-    return constantCompilerTask.constantCompiler.constantSystem;
-  }
-
-  BackendConstantEnvironment get constants => constantCompilerTask;
-
-  DartConstantTask constantCompilerTask;
-
   final Set<ClassElement> usedTypeLiterals = new Set<ClassElement>();
 
   /**
@@ -106,7 +98,6 @@ class DartBackend extends Backend {
         reexportingLibraries = <Element, LibraryElement>{},
         forceStripTypes = strips.indexOf('types') != -1,
         stripAsserts = strips.indexOf('asserts') != -1,
-        constantCompilerTask  = new DartConstantTask(compiler),
         super(compiler);
 
   bool classNeedsRti(ClassElement cls) => false;
@@ -590,56 +581,3 @@ compareElements(e0, e1) {
 
 List<Element> sortElements(Iterable<Element> elements) =>
     sorted(elements, compareElements);
-
-/// [ConstantCompilerTask] for compilation of constants for the Dart backend.
-///
-/// Since this task needs no distinction between frontend and backend constants
-/// it also serves as the [BackendConstantEnvironment].
-class DartConstantTask extends ConstantCompilerTask
-    implements BackendConstantEnvironment {
-  final DartConstantCompiler constantCompiler;
-
-  DartConstantTask(Compiler compiler)
-    : this.constantCompiler = new DartConstantCompiler(compiler),
-      super(compiler);
-
-  String get name => 'ConstantHandler';
-
-  Constant getConstantForVariable(VariableElement element) {
-    return constantCompiler.getConstantForVariable(element);
-  }
-
-  Constant getConstantForNode(Node node, TreeElements elements) {
-    return constantCompiler.getConstantForNode(node, elements);
-  }
-
-  Constant getConstantForMetadata(MetadataAnnotation metadata) {
-    return metadata.value;
-  }
-
-  Constant compileConstant(VariableElement element) {
-    return measure(() {
-      return constantCompiler.compileConstant(element);
-    });
-  }
-
-  void compileVariable(VariableElement element) {
-    measure(() {
-      constantCompiler.compileVariable(element);
-    });
-  }
-
-  Constant compileNode(Node node, TreeElements elements) {
-    return measure(() {
-      return constantCompiler.compileNodeWithDefinitions(node, elements);
-    });
-  }
-
-  Constant compileMetadata(MetadataAnnotation metadata,
-                           Node node,
-                           TreeElements elements) {
-    return measure(() {
-      return constantCompiler.compileMetadata(metadata, node, elements);
-    });
-  }
-}