Deprecate Math object in corelib in favor of dart:math library.

samples/third_party/dromaeo/Dromaeo.dart

 #import('dart:html');
 #import('dart:json');
+#import('dart:math', prefix: 'Math');
 #import('Suites.dart');
 
 main() {
   new Dromaeo().run();
 }
 
 class SuiteController {
   final SuiteDescription _suiteDescription;
   final IFrameElement _suiteIframe;
 
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   }
 
   Element _byId(String id) {
     return document.query('#$id');
   }
 
   int get _suitesTotal {
     return _suiteControllers.length;
   }
 }