Get rid of refreshDisplay update algorithm

It seems patchDisplay is always faster

Closes #233

lib/codemirror.js

@@ -880,13 +880,7 @@ var CodeMirror = (function() {
       if (!updates.length) return;
       var th = textHeight(), gutterDisplay = gutter.style.display;
       lineDiv.style.display = gutter.style.display = "none";
-      // If more than 30% of the screen needs update, just do a full
-      // redraw (which is quicker than patching)
-      if (changedLines > (visible.to - visible.from) * .3)
-        refreshDisplay(from = Math.max(visible.from - 10, 0), to = Math.min(visible.to + 7, doc.size));
-      // Otherwise, only update the stuff that needs updating.
-      else
-        patchDisplay(updates);
+      patchDisplay(updates);
       lineDiv.style.display = "";
 
       // Position the mover div to align with the lines it's supposed
@@ -930,25 +924,6 @@ var CodeMirror = (function() {
       updateCursor();
     }
 
-    function refreshDisplay(from, to) {
-      var start = {line: from, ch: 0}, inSel = posLess(sel.from, start) && !posLess(sel.to, start);
-      var i = from, html = [];
-      doc.iter(from, to, function(line) {
-        var ch1 = null, ch2 = null;
-        if (inSel) {
-          ch1 = 0;
-          if (sel.to.line == i) {inSel = false; ch2 = sel.to.ch;}
-        }
-        else if (sel.from.line == i) {
-          if (sel.to.line == i) {ch1 = sel.from.ch; ch2 = sel.to.ch;}
-          else {inSel = true; ch1 = sel.from.ch;}
-        }
-        if (line.hidden) html.push("<pre></pre>");
-        else html.push(line.getHTML(ch1, ch2, true));
-        ++i;
-      });
-      lineDiv.innerHTML = html.join("");
-    }
     function patchDisplay(updates) {
       // Slightly different algorithm for IE (badInnerHTML), since
       // there .innerHTML on PRE nodes is dumb, and discards