Move implementation from KernelToElementMapImpl to *BaseImpl and *ForImpactImpl

pkg/compiler/lib/src/js_model/js_strategy.dart

Index: pkg/compiler/lib/src/js_model/js_strategy.dart
diff --git a/pkg/compiler/lib/src/js_model/js_strategy.dart b/pkg/compiler/lib/src/js_model/js_strategy.dart
index f4f94ac07e856d0654668caf8e2d0d01bb0c1b9d..e2279f667207b8e029c3634e5b8f9665c8ca3302 100644
--- a/pkg/compiler/lib/src/js_model/js_strategy.dart
+++ b/pkg/compiler/lib/src/js_model/js_strategy.dart
@@ -48,7 +48,12 @@ class JsBackendStrategy implements KernelBackendStrategy {
       KernelFrontEndStrategy strategy = _compiler.frontendStrategy;
       KernelToElementMapForBuilding elementMap = strategy.elementMap;
       _elementMap = new JsKernelToElementMap(
-          _map, _elementEnvironment, _commonElements, elementMap);
+          _compiler.reporter,
+          _compiler.environment,
+          _map,
+          _elementEnvironment,
+          _commonElements,
+          elementMap);
     }
     return _elementMap;
   }