Reapply "Refactor constant part." (r4958) with fixes.

frog/leg/native_handler.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.
 
 #library('native');
 #import('../../lib/uri/uri.dart');
 #import('leg.dart');
 #import('elements/elements.dart');
 #import('scanner/scannerlib.dart');
 #import('ssa/ssa.dart');
@@ skipping 196 matching lines @@
         builder.add(instruction);
         List<HInstruction> elseInputs = new List<HInstruction>.from(inputs);
         elseInputs.add(instruction);
         String params = arguments.isEmpty() ? '' : ', $foreignParameters';
         jsCode = new SourceString('\$${i}.call(\$0$params)');
         elseInstruction =
             new HForeign(jsCode, const SourceString('Object'), elseInputs);
         builder.add(elseInstruction);
       }
 
-      HLiteral literal = builder.graph.addNewLiteralString(
+      HLiteral literal = builder.graph.addConstantString(
           new DartString.literal('$dartMethodName'));
       SourceString jsCode = new SourceString(
           'Object.getPrototypeOf(\$0).hasOwnProperty(\$1)');
       builder.push(new HForeign(
           jsCode, const SourceString('Object'),
           <HInstruction>[builder.localsHandler.readThis(), literal]));
 
       builder.handleIf(visitThen, visitElse);
 
       HPhi phi = new HPhi.manyInputs(
           null, <HInstruction>[thenInstruction, elseInstruction]);
       builder.current.addPhi(phi);
       builder.stack.add(phi);
     }
 
   } else if (!node.arguments.tail.isEmpty()) {
     builder.compiler.cancel('More than one argument to native');
   } else {
     LiteralString jsCode = node.arguments.head;
     int start = jsCode.value.slowToString()[0] === '@' ? 1 : 0;
     builder.push(new HForeign(builder.unquote(jsCode, start),
                               const SourceString('Object'),
                               <HInstruction>[]));
   }
 }