fix(modal): check for overflow hidden

Check if appendToElement has scrolling disabled before adding
the scrollbar padding.

Fixes #6037
Closes #6041

Author: RobJacobs

src/modal/modal.js

@@ -487,9 +487,11 @@ angular.module('ui.bootstrap.modal', ['ui.bootstrap.stackedMap', 'ui.bootstrap.p
           }
           $compile(backdropDomEl)(backdropScope);
           $animate.enter(backdropDomEl, appendToElement);
-          scrollbarPadding = $uibPosition.scrollbarPadding(appendToElement);
-          if (scrollbarPadding.heightOverflow && scrollbarPadding.scrollbarWidth) {
-            appendToElement.css({paddingRight: scrollbarPadding.right + 'px'});
+          if ($uibPosition.isScrollable(appendToElement)) {
+            scrollbarPadding = $uibPosition.scrollbarPadding(appendToElement);
+            if (scrollbarPadding.heightOverflow && scrollbarPadding.scrollbarWidth) {
+              appendToElement.css({paddingRight: scrollbarPadding.right + 'px'});
+            }
           }
         }