Remove call-indirections from type tests.

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

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of js_backend;
 
 /**
  * A function element that represents a closure call. The signature is copied
  * from the given element.
  */
@@ skipping 1157 matching lines @@
         addInstanceMember(member, builder);
       }
     }
 
     classElement.implementation.forEachMember(
         visitMember,
         includeBackendMembers: true,
         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}) {
       RuntimeTypes rti = backend.rti;
       // TODO(karlklose): support typedefs with variables.
       jsAst.Expression expression;
       bool needsNativeCheck = nativeEmitter.requiresNativeIsCheck(other);
       if (other.kind == ElementKind.CLASS) {
         String substitution = rti.getSupertypeSubstitution(classElement, other,
             alwaysGenerateFunction: true);
         if (substitution != null) {
           expression = new jsAst.LiteralExpression(substitution);
         } else if (emitNull || needsNativeCheck) {
           expression = new jsAst.LiteralNull();
         }
       }
       if (expression != null) {
-        if (needsNativeCheck) {
-          expression = js.fun([], js.return_(expression));
-        }
         builder.addProperty(namer.substitutionName(other), expression);
       }
     }
 
     generateIsTestsOn(classElement, generateIsTest, generateSubstitution);
 
     if (identical(classElement, compiler.objectClass)
         && compiler.enabledNoSuchMethod) {
       // Emit the noSuchMethod handlers on the Object prototype now,
       // so that the code in the dynamicFunction helper can find
@@ skipping 1828 matching lines @@
 """;
 const String HOOKS_API_USAGE = """
 // The code supports the following hooks:
 // dartPrint(message)   - if this function is defined it is called
 //                        instead of the Dart [print] method.
 // dartMainRunner(main) - if this function is defined, the Dart [main]
 //                        method will not be invoked directly.
 //                        Instead, a closure that will invoke [main] is
 //                        passed to [dartMainRunner].
 """;