Remove call-indirections from type tests.

sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart

Index: sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart
diff --git a/sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart b/sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart
index 482116299e3a2c0521919bc7760fd776998c0381..0dea08d7d9a2d6b40c8a5b322c3bb6664df90d57 100644
--- a/sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart
+++ b/sdk/lib/_internal/compiler/implementation/js_backend/emitter.dart
@@ -1175,17 +1175,11 @@ class CodeEmitterTask extends CompilerTask {
         includeSuperMembers: false);
 
     void generateIsTest(Element other) {
-      jsAst.Expression code;
       if (other == compiler.objectClass && other != classElement) {
         // Avoid emitting [:$isObject:] on all classes but [Object].
         return;
       }
-      if (nativeEmitter.requiresNativeIsCheck(other)) {
-        code = js.fun([], [js.return_(true)]);
-      } else {
-        code = js('true');
-      }
-      builder.addProperty(namer.operatorIs(other), code);
+      builder.addProperty(namer.operatorIs(other), js('true'));
     }
 
     void generateSubstitution(Element other, {bool emitNull: false}) {
@@ -1203,9 +1197,6 @@ class CodeEmitterTask extends CompilerTask {
         }
       }
       if (expression != null) {
-        if (needsNativeCheck) {
-          expression = js.fun([], js.return_(expression));
-        }
         builder.addProperty(namer.substitutionName(other), expression);
       }
     }