Cancel out unwanted editor's css for autocomplete dialog

lib/ace/autocomplete/popup.js

@@ -304,6 +304,11 @@ dom.importCssString("\
     position: absolute;\
     z-index: 2;\
 }\
+.ace_editor.ace_autocomplete .ace_scroller {\
+   background: none;\
+   border: none;\
+   box-shadow: none;\
+}\
 .ace_rightAlignedText {\
     color: gray;\
     display: inline-block;\