Revert "Move towards using WorldImpact for codegen"

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

Index: pkg/compiler/lib/src/js_backend/js_interop_analysis.dart
diff --git a/pkg/compiler/lib/src/js_backend/js_interop_analysis.dart b/pkg/compiler/lib/src/js_backend/js_interop_analysis.dart
index e43fb682c7b0248d42e6a9d2d3dd1b67aae24478..da89b34344692aaae40b30318508edbea62755d5 100644
--- a/pkg/compiler/lib/src/js_backend/js_interop_analysis.dart
+++ b/pkg/compiler/lib/src/js_backend/js_interop_analysis.dart
@@ -116,7 +116,7 @@ class JsInteropAnalysis {
 
       // Skip classes that are completely unreachable. This should only happen
       // when all of jsinterop types are unreachable from main.
-      if (!backend.compiler.openWorld.isImplemented(classElement)) return;
+      if (!backend.compiler.closedWorld.isImplemented(classElement)) return;
 
       if (!classElement.implementsInterface(helpers.jsJavaScriptObjectClass)) {
         backend.reporter.reportErrorMessage(classElement,