Revert "Redo "Make dart2js typed_data implementation classes private""

sdk/lib/_internal/compiler/implementation/ssa/builder.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 ssa;
 
 /**
  * A special element for the extra parameter taken by intercepted
  * methods. We need to override [Element.computeType] because our
  * optimizers may look at its declared type.
@@ skipping 4023 matching lines @@
             TypeMaskFactory.inferredForNode(sourceElement, send, compiler);
         return inferred.containsAll(compiler)
             ? backend.extendableArrayType
             : inferred;
       } else if (Elements.isConstructorOfTypedArraySubclass(
                     originalElement, compiler)) {
         isFixedList = true;
         TypeMask inferred =
             TypeMaskFactory.inferredForNode(sourceElement, send, compiler);
         ClassElement cls = element.getEnclosingClass();
-        assert(cls.thisType.element.isNative());
         return inferred.containsAll(compiler)
             ? new TypeMask.nonNullExact(cls.thisType.element)
             : inferred;
       } else if (element.isGenerativeConstructor()) {
         ClassElement cls = element.getEnclosingClass();
         return new TypeMask.nonNullExact(cls.thisType.element);
       } else {
         return TypeMaskFactory.inferredReturnTypeForElement(
             originalElement, compiler);
       }
@@ skipping 2350 matching lines @@
     DartType unaliased = type.unalias(builder.compiler);
     if (unaliased is TypedefType) throw 'unable to unalias $type';
     unaliased.accept(this, builder);
   }
 
   void visitDynamicType(DynamicType type, SsaFromAstMixin builder) {
     ClassElement cls = builder.compiler.findHelper('DynamicRuntimeType');
     builder.push(new HDynamicType(type, new TypeMask.exact(cls)));
   }
 }