We can actually map the Dart shift right to the JavaScript one under certain conditions.

sdk/lib/_internal/compiler/implementation/ssa/tracer.dart

 // Copyright (c) 2013, 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.
 
 library tracer;
 
 import 'dart:async' show EventSink;
 
 import 'ssa.dart';
 import '../js_backend/js_backend.dart';
@@ skipping 408 matching lines @@
       if (i > 0) buffer.write(", ");
       buffer.write(temporaryId(phi.inputs[i]));
     }
     buffer.write(")");
     return buffer.toString();
   }
 
   String visitReturn(HReturn node) => "Return ${temporaryId(node.inputs[0])}";
 
   String visitShiftLeft(HShiftLeft node) => handleInvokeBinary(node, '<<');
+  String visitShiftRight(HShiftRight node) => handleInvokeBinary(node, '>>');
 
   String visitStatic(HStatic node)
       => "Static ${node.element.name}";
 
   String visitLazyStatic(HLazyStatic node)
       => "LazyStatic ${node.element.name}";
 
   String visitOneShotInterceptor(HOneShotInterceptor node)
       => visitInvokeDynamic(node, "one shot interceptor");
 
@@ skipping 75 matching lines @@
 
   String visitTypeKnown(HTypeKnown node) {
     assert(node.inputs.length == 1);
     return "TypeKnown: ${temporaryId(node.checkedInput)} is ${node.knownType}";
   }
 
   String visitRangeConversion(HRangeConversion node) {
     return "RangeConversion: ${node.checkedInput}";
   }
 }