Remove JavaScriptBackend from ClosedWorldBase

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 65620fda8e12fd01ac36f67a8728c26b339a147f..034108683dc2186a30d05e28d96cec084691a518 100644
--- a/pkg/compiler/lib/src/compiler.dart
+++ b/pkg/compiler/lib/src/compiler.dart
@@ -626,6 +626,7 @@ abstract class Compiler {
 
         processQueue(resolutionEnqueuer, mainMethod, libraryLoader.libraries,
             onProgress: showResolutionProgress);
+        backend.onResolutionEnd();
         resolutionEnqueuer.logSummary(reporter.log);
 
         _reporter.reportSuppressedMessagesSummary();
@@ -704,7 +705,7 @@ abstract class Compiler {
   ClosedWorldRefiner closeResolution() {
     phase = PHASE_DONE_RESOLVING;
 
-    ClosedWorldImpl world = resolutionWorldBuilder.closeWorld(reporter);
+    ClosedWorldImpl world = resolutionWorldBuilder.closeWorld();
     // Compute whole-program-knowledge that the backend needs. (This might
     // require the information computed in [world.closeWorld].)
     backend.onResolutionComplete(world, world);