Smaller line-height in the file tree.

services/web/public/stylesheets/app/editor/file-tree.less

@@ -52,7 +52,7 @@
 		}
 
 		li {
-			line-height: 2.6;
+			line-height: @file-tree-line-height;
 			position: relative;
 
 			.entity {

services/web/public/stylesheets/core/_common-variables.less

@@ -906,6 +906,7 @@
 
 // Editor file-tree
 @file-tree-bg                    : transparent;
+@file-tree-line-height           : 2.6;
 @file-tree-item-color            : @gray-darker;
 @file-tree-item-toggle-color     : @gray;
 @file-tree-item-icon-color       : @gray-light;

services/web/public/stylesheets/core/ol-variables.less

@@ -174,6 +174,7 @@
 @toolbar-border-bottom          : 1px solid @toolbar-border-color;
 // Editor file-tree
 @file-tree-bg                   : @ol-blue-gray-4;
+@file-tree-line-height          : 2.05;
 @file-tree-item-color           : #FFF;
 @file-tree-item-input-color     : @ol-blue-gray-5;
 @file-tree-item-toggle-color    : @ol-blue-gray-2;