Revert "Revert "Use interceptor convention for methods declared on native classes.""

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 303 matching lines @@
       } else if (cls == builder.backend.jsDoubleClass) {
         type = HType.DOUBLE;
       } else if (cls == builder.backend.jsNullClass) {
         type = HType.NULL;
       } else if (cls == builder.backend.jsBoolClass) {
         type = HType.BOOLEAN;
       } else if (cls == builder.backend.jsFunctionClass) {
         type = HType.UNKNOWN;
       } else if (cls != compiler.objectClass) {
         JavaScriptBackend backend = compiler.backend;
-        assert(!backend.isInterceptorClass(cls));
-        name = const SourceString('_');
+        if (!backend.isInterceptorClass(cls)) {
+          name = const SourceString('_');
+        }
       }
       Element parameter = new InterceptedElement(type, name, element);
       HParameterValue value = new HParameterValue(parameter);
       builder.graph.explicitReceiverParameter = value;
       builder.graph.entry.addAfter(
           directLocals[closureData.thisElement], value);
       if (builder.backend.isInterceptorClass(cls.declaration)) {
         // Only use the extra parameter in intercepted classes.
         directLocals[closureData.thisElement] = value;
       }
@@ skipping 4787 matching lines @@
           new HSubGraphBlockInformation(elseBranch.graph));
 
     HBasicBlock conditionStartBlock = conditionBranch.block;
     conditionStartBlock.setBlockFlow(info, joinBlock);
     SubGraph conditionGraph = conditionBranch.graph;
     HIf branch = conditionGraph.end.last;
     assert(branch is HIf);
     branch.blockInformation = conditionStartBlock.blockFlow;
   }
 }