Split implementation of KernelToElementMapImpl

pkg/compiler/lib/src/compiler.dart

Index: pkg/compiler/lib/src/compiler.dart
diff --git a/pkg/compiler/lib/src/compiler.dart b/pkg/compiler/lib/src/compiler.dart
index decf1df0cb9b55e705d52239074863d834b276ee..cbf31ba0454460799cf3eca6a406da17bc121cb4 100644
--- a/pkg/compiler/lib/src/compiler.dart
+++ b/pkg/compiler/lib/src/compiler.dart
@@ -192,7 +192,7 @@ abstract class Compiler {
         ? new KernelFrontEndStrategy(reporter, environment)
         : new ResolutionFrontEndStrategy(this);
     backendStrategy = options.loadFromDill
-        ? new KernelBackendStrategyImpl(this)
+        ? new KernelBackendStrategy(this)
         : new ElementBackendStrategy(this);
     _resolution = createResolution();