Add ClosedWorld.elementEnvironment and remove Compiler.elementEnvironment

pkg/compiler/lib/src/js_emitter/code_emitter_task.dart

Index: pkg/compiler/lib/src/js_emitter/code_emitter_task.dart
diff --git a/pkg/compiler/lib/src/js_emitter/code_emitter_task.dart b/pkg/compiler/lib/src/js_emitter/code_emitter_task.dart
index f8ba32ed27011d2f5f8d01af456f25bbf8d2f9b2..59c06ae547854be6daa84c56fb5de096d28957f5 100644
--- a/pkg/compiler/lib/src/js_emitter/code_emitter_task.dart
+++ b/pkg/compiler/lib/src/js_emitter/code_emitter_task.dart
@@ -182,7 +182,7 @@ class CodeEmitterTask extends CompilerTask {
           backend.mirrorsData,
           backend.rtiEncoder);
       typeTestRegistry = new TypeTestRegistry(
-          codegenWorldBuilder, closedWorld, compiler.elementEnvironment);
+          codegenWorldBuilder, closedWorld, closedWorld.elementEnvironment);
     });
   }
 
@@ -192,7 +192,7 @@ class CodeEmitterTask extends CompilerTask {
       ProgramBuilder programBuilder = new ProgramBuilder(
           compiler.options,
           compiler.reporter,
-          compiler.elementEnvironment,
+          closedWorld.elementEnvironment,
           closedWorld.commonElements,
           compiler.types,
           compiler.deferredLoadTask,