Fix problem where focus() caused the cursor to jump to start on IE8

Author: marijnh

lib/codemirror.js

@@ -118,7 +118,7 @@ var CodeMirror = (function() {
       setValue: operation(setValue),
       getSelection: getSelection,
       replaceSelection: operation(replaceSelection),
-      focus: function(){focusInput(); onFocus(); fastPoll();},
+      focus: function(){focusInput(); onFocus(); prepareInput(); fastPoll();},
       setOption: function(option, value) {
         options[option] = value;
         if (option == "lineNumbers" || option == "gutter") gutterChanged();