fix +7009 Selection is invisible when using Classic light gray and Cloud9 night

plugins/c9.ide.layout.classic/themes/default-dark-gray.less

@@ -52,7 +52,7 @@
 @ace-cloud9-day-background: lighten(#F8F8F8, @lighten-chrome);
 @ace-cloud9-night-gutter: @panel-background;
 @ace-cloud9-night-background: lighten(#181818, @lighten-chrome);
-@ace-cloud9-night-active-line: lighten(#292929, @lighten-chrome);
+@ace-cloud9-night-active-line: rgba(68, 68, 68, 0.78); // todo make selection lighter #5A5A5A too?
 @ace-gutter-font-smoothing: true;
 @ace-gutter-shadow: 1px 0 rgba(255, 255, 255, 0.75) inset;