Merge pull request #1940 from Carreau/completer-css-patch

Fix completer css on some Chrome versions (was causing completer to be drawn at the wrong size).

Fixes  #1833

IPython/frontend/html/notebook/static/css/notebook.css

@@ -278,7 +278,7 b' div.text_cell_render {'
 .completions {
     position: absolute;
     z-index: 10;
-    overflow: auto;
+    overflow: hidden;
     border: 1px solid grey;
 }
 
@@ -288,6 +288,7 b' div.text_cell_render {'
     border: none;
     padding: 0px;
     margin: 0px;
+    overflow: auto;
     font-family: monospace;
 }