Extract interceptor calls from raw is-checks.

sdk/lib/_internal/compiler/implementation/js_backend/backend.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;
 
 class JavaScriptItemCompilationContext extends ItemCompilationContext {
   final Set<HInstruction> boundsChecked;
 
   JavaScriptItemCompilationContext()
@@ skipping 1266 matching lines @@
                 ? const PropertyCheckedModeHelper(
                     const SourceString('propertyTypeCast'))
                 : const PropertyCheckedModeHelper(
                     const SourceString('propertyTypeCheck'));
           }
         }
       }
     }
   }
 
+  /**
+   * Returns [:true:] if the checking of [type] is performed directly on the
+   * object and not on an interceptor.
+   */
+  bool hasDirectCheckFor(DartType type) {
+    Element element = type.element;
+    return element == compiler.stringClass ||
+        element == compiler.boolClass ||
+        element == compiler.numClass ||
+        element == compiler.intClass ||
+        element == compiler.doubleClass ||
+        element == jsArrayClass ||
+        element == jsMutableArrayClass ||
+        element == jsExtendableArrayClass ||
+        element == jsFixedArrayClass;
+  }
+
   Element getExceptionUnwrapper() {
     return compiler.findHelper(const SourceString('unwrapException'));
   }
 
   Element getThrowRuntimeError() {
     return compiler.findHelper(const SourceString('throwRuntimeError'));
   }
 
   Element getThrowAbstractClassInstantiationError() {
     return compiler.findHelper(
@@ skipping 324 matching lines @@
     copy(constant.values);
     copy(constant.protoValue);
     copy(constant);
   }
 
   void visitConstructed(ConstructedConstant constant) {
     copy(constant.fields);
     copy(constant);
   }
 }