style($rootScope): remove trailing whitespace

Author: petebacondarwin

src/ng/rootScope.js

@@ -254,7 +254,7 @@ function $RootScopeProvider() {
        *
        * - The `watchExpression` is called on every call to {@link ng.$rootScope.Scope#$digest
        *   $digest()} and should return the value that will be watched. (`watchExpression` should not change
-       *   its value when executed multiple times with the same input because it may be executed multiple 
+       *   its value when executed multiple times with the same input because it may be executed multiple
        *   times by {@link ng.$rootScope.Scope#$digest $digest()}. That is, `watchExpression` should be
        *   [idempotent](http://en.wikipedia.org/wiki/Idempotence).
        * - The `listener` is called only when the value from the current `watchExpression` and the