Use the explicit path - minor optimization

Author: gautamdsheth

src/controls/pagination/Pagination.tsx

@@ -1,5 +1,5 @@
 import * as React from "react";
-import { PrimaryButton, DefaultButton } from 'office-ui-fabric-react';
+import { PrimaryButton, DefaultButton } from 'office-ui-fabric-react/lib/Button';
 import styles from "./Pagination.module.scss";
 
 export interface IPaginationProps {

src/controls/treeView/TreeItem.tsx

@@ -2,7 +2,7 @@ import * as React from 'react';
 import styles from './TreeView.module.scss';
 import { Checkbox } from 'office-ui-fabric-react/lib/Checkbox';
 import { Icon } from 'office-ui-fabric-react/lib/Icon';
-import { IconButton } from 'office-ui-fabric-react';
+import { IconButton } from 'office-ui-fabric-react/lib/Button';
 import * as strings from 'ControlStrings';
 import { ITreeItem } from './ITreeItem';
 import { TreeViewSelectionMode } from './ITreeViewProps';