refactor: IS_DART === false

modules/@angular/facade/src/lang.ts

@@ -51,8 +51,6 @@ export function scheduleMicroTask(fn: Function) {
   Zone.current.scheduleMicroTask('scheduleMicrotask', fn);
 }
 
-export const IS_DART = false;
-
 // Need to declare a new variable for global here since TypeScript
 // exports the original value of the symbol.
 var _global: BrowserNodeGlobal = globalScope;