Use JavaScript runtime semantics when constant folding.

lib/compiler/implementation/apiimpl.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('leg_apiimpl');
 
 #import('dart:uri');
 
 #import('../compiler.dart', prefix: 'api');
 #import('leg.dart', prefix: 'leg');
@@ skipping 12 matching lines @@
   bool mockableLibraryUsed = false;
 
   Compiler(this.provider, this.handler, this.libraryRoot, this.packageRoot,
            List<String> options)
       : this.options = options,
         super(
             tracer: new ssa.HTracer(),
             enableTypeAssertions: hasOption(options, '--enable-checked-mode'),
             enableUserAssertions: hasOption(options, '--enable-checked-mode'),
             enableMinification: hasOption(options, '--minify'),
-            emitJavascript: !hasOption(options, '--output-type=dart'),
+            emitJavaScript: !hasOption(options, '--output-type=dart'),
             cutDeclarationTypes: hasOption(options, '--cut-declaration-types'));
 
   static bool hasOption(List<String> options, String option) {
     return options.indexOf(option) >= 0;
   }
 
   String lookupLibraryPath(String dartLibraryName) {
     LibraryInfo info = LIBRARIES[dartLibraryName];
     if (info === null) return null;
     if (!info.isDart2jsLibrary) return null;
@@ skipping 100 matching lines @@
       handler(translateUri(span.uri, null), span.begin, span.end,
               message, kind);
     }
   }
 
   bool get isMockCompilation {
     return mockableLibraryUsed
       && (options.indexOf('--allow-mock-compilation') !== -1);
   }
 }