Revert "Move towards using WorldImpact for codegen"

pkg/compiler/lib/src/js_backend/backend_impact.dart

Index: pkg/compiler/lib/src/js_backend/backend_impact.dart
diff --git a/pkg/compiler/lib/src/js_backend/backend_impact.dart b/pkg/compiler/lib/src/js_backend/backend_impact.dart
index 5572e2293ba9ec7347110187650abadb4bc23f2e..3ab0227a795e776694fed5d266e48663cb7d470a 100644
--- a/pkg/compiler/lib/src/js_backend/backend_impact.dart
+++ b/pkg/compiler/lib/src/js_backend/backend_impact.dart
@@ -22,7 +22,7 @@ class BackendImpact {
   final List<ClassElement> instantiatedClasses;
   final List<BackendImpact> otherImpacts;
 
-  const BackendImpact(
+  BackendImpact(
       {this.staticUses: const <Element>[],
       this.dynamicUses: const <Selector>[],
       this.instantiatedTypes: const <InterfaceType>[],
@@ -598,19 +598,4 @@ class BackendImpacts {
     }
     return _closure;
   }
-
-  BackendImpact _interceptorUse;
-
-  BackendImpact get interceptorUse {
-    if (_interceptorUse == null) {
-      _interceptorUse = new BackendImpact(staticUses: [
-        helpers.getNativeInterceptorMethod
-      ], instantiatedClasses: [
-        helpers.jsJavaScriptObjectClass,
-        helpers.jsPlainJavaScriptObjectClass,
-        helpers.jsJavaScriptFunctionClass
-      ]);
-    }
-    return _interceptorUse;
-  }
 }