Add ConstantUse to WorldImpact

pkg/compiler/lib/src/common/codegen.dart

Index: pkg/compiler/lib/src/common/codegen.dart
diff --git a/pkg/compiler/lib/src/common/codegen.dart b/pkg/compiler/lib/src/common/codegen.dart
index c733c1cad25f9bdfb29879fc4b83be04b2ed36b7..6ac632897cb19cd2dd74a14b442a3655705506b7 100644
--- a/pkg/compiler/lib/src/common/codegen.dart
+++ b/pkg/compiler/lib/src/common/codegen.dart
@@ -17,7 +17,7 @@ import '../elements/elements.dart'
         MemberElement,
         ResolvedAst;
 import '../js_backend/backend.dart' show JavaScriptBackend;
-import '../universe/use.dart' show DynamicUse, StaticUse, TypeUse;
+import '../universe/use.dart' show ConstantUse, DynamicUse, StaticUse, TypeUse;
 import '../universe/world_impact.dart'
     show WorldImpact, WorldImpactBuilderImpl, WorldImpactVisitor;
 import '../util/util.dart' show Pair, Setlet;
@@ -26,8 +26,6 @@ import 'work.dart' show WorkItem;
 class CodegenImpact extends WorldImpact {
   const CodegenImpact();
 
-  Iterable<ConstantValue> get compileTimeConstants => const <ConstantValue>[];
-
   Iterable<Pair<ResolutionDartType, ResolutionDartType>>
       get typeVariableBoundsSubtypeChecks {
     return const <Pair<ResolutionDartType, ResolutionDartType>>[];
@@ -47,7 +45,6 @@ class CodegenImpact extends WorldImpact {
 }
 
 class _CodegenImpact extends WorldImpactBuilderImpl implements CodegenImpact {
-  Setlet<ConstantValue> _compileTimeConstants;
   Setlet<Pair<ResolutionDartType, ResolutionDartType>>
       _typeVariableBoundsSubtypeChecks;
   Setlet<String> _constSymbols;
@@ -64,19 +61,6 @@ class _CodegenImpact extends WorldImpactBuilderImpl implements CodegenImpact {
     typeUses.forEach(visitor.visitTypeUse);
   }
 
-  void registerCompileTimeConstant(ConstantValue constant) {
-    if (_compileTimeConstants == null) {
-      _compileTimeConstants = new Setlet<ConstantValue>();
-    }
-    _compileTimeConstants.add(constant);
-  }
-
-  Iterable<ConstantValue> get compileTimeConstants {
-    return _compileTimeConstants != null
-        ? _compileTimeConstants
-        : const <ConstantValue>[];
-  }
-
   void registerTypeVariableBoundsSubtypeCheck(
       ResolutionDartType subtype, ResolutionDartType supertype) {
     if (_typeVariableBoundsSubtypeChecks == null) {
@@ -178,8 +162,8 @@ class CodegenRegistry {
     worldImpact.registerTypeUse(typeUse);
   }
 
-  void registerCompileTimeConstant(ConstantValue constant) {
-    worldImpact.registerCompileTimeConstant(constant);
+  void registerConstantUse(ConstantUse constantUse) {
+    worldImpact.registerConstantUse(constantUse);
   }
 
   void registerTypeVariableBoundsSubtypeCheck(