Compute frontend/backend specific constants.

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

Index: sdk/lib/_internal/compiler/implementation/compiler.dart
diff --git a/sdk/lib/_internal/compiler/implementation/compiler.dart b/sdk/lib/_internal/compiler/implementation/compiler.dart
index 8cba4eb513cf4160a2f1f02f165d960f50a1d1be..824f203df824104f8e086dfb695e6f457a5b2d66 100644
--- a/sdk/lib/_internal/compiler/implementation/compiler.dart
+++ b/sdk/lib/_internal/compiler/implementation/compiler.dart
@@ -74,11 +74,20 @@ class DeferredTask {
 
 abstract class Backend {
   final Compiler compiler;
-  final ConstantSystem constantSystem;
 
-  Backend(this.compiler,
-          [ConstantSystem constantSystem = DART_CONSTANT_SYSTEM])
-      : this.constantSystem = constantSystem;
+  Backend(this.compiler);
+
+  /// The [ConstantSystem] used to interpret compile-time constants for this
+  /// backend.
+  ConstantSystem get constantSystem;
+
+  /// The constant environment for the backend interpretation of compile-time
+  /// constants.
+  BackendConstantEnvironment get constants;
+
+  /// The compiler task responsible for the compilation of constants for both
+  /// the frontend and the backend.
+  ConstantCompilerTask get constantCompilerTask;
 
   // Given a [FunctionElement], return a buffer with the code generated for it
   // or null if no code was generated.
@@ -566,7 +575,11 @@ abstract class Compiler implements DiagnosticListener {
   IrBuilderTask irBuilder;
   ti.TypesTask typesTask;
   Backend backend;
-  ConstantHandler constantHandler;
+
+  /// The constant environment for the frontend interpretation of compile-time
+  /// constants.
+  ConstantEnvironment constants;
+
   EnqueueTask enqueuer;
   DeferredLoadTask deferredLoadTask;
   MirrorUsageAnalyzerTask mirrorUsageAnalyzerTask;
@@ -679,12 +692,12 @@ abstract class Compiler implements DiagnosticListener {
       dietParser = new DietParserTask(this),
       parser = new ParserTask(this),
       patchParser = new PatchParserTask(this),
-      resolver = new ResolverTask(this),
+      resolver = new ResolverTask(this, backend.constantCompilerTask),
       closureToClassMapper = new closureMapping.ClosureTask(this, closureNamer),
       checker = new TypeCheckerTask(this),
       irBuilder = new IrBuilderTask(this),
       typesTask = new ti.TypesTask(this),
-      constantHandler = new ConstantHandler(this, backend.constantSystem),
+      constants = backend.constantCompilerTask,
       deferredLoadTask = new DeferredLoadTask(this),
       mirrorUsageAnalyzerTask = new MirrorUsageAnalyzerTask(this),
       enqueuer = new EnqueueTask(this),
@@ -943,8 +956,8 @@ abstract class Compiler implements DiagnosticListener {
 
     dynamicClass.ensureResolved(this);
 
-    proxyConstant = constantHandler.compileVariable(
-        coreLibrary.find('proxy'), isConst: true);
+    proxyConstant =
+        resolver.constantCompiler.compileConstant(coreLibrary.find('proxy'));
   }
 
   Element _unnamedListConstructor;