Reverting this revert, since it does not seem to have caused the breakage.

chrome/browser/resources/options/language_options.css

Index: chrome/browser/resources/options/language_options.css
===================================================================
--- chrome/browser/resources/options/language_options.css	(revision 114404)
+++ chrome/browser/resources/options/language_options.css	(working copy)
@@ -39,6 +39,16 @@
   width: 300px;
 }
 
+/* On OS X we use the native OS spellchecker, so don't display the dictionary */
+/* pane. */
+html[os=mac] .language-options-left {
+ background-color: white;
+}
+
+html[os=mac] .language-options-right {
+ visibility: hidden;
+}
+
 .language-options-lower-left {
   -webkit-box-flex: 0;
   -webkit-padding-start: 12px;