DevTools: Don't refresh CodeMirror if it is hidden

CodeMirror.refresh is expensive, and calling it when CodeMirror is hidden breaks the gutters.

BUG=none

Review-Url: https://codereview.chromium.org/2342643002
Cr-Commit-Position: refs/heads/master@{#418684}

third_party/WebKit/Source/devtools/front_end/source_frame/SourcesTextEditor.js

@@ -174,7 +174,7 @@ WebInspector.SourcesTextEditor.prototype = {
             this._gutters.push(type);
 
         this.codeMirror().setOption("gutters", this._gutters.slice());
-        this.codeMirror().refresh();
+        this.refresh();
     },
 
     /**
@@ -182,9 +182,12 @@ WebInspector.SourcesTextEditor.prototype = {
      */
     uninstallGutter: function(type)
     {
-        this._gutters = this._gutters.filter(gutter => gutter !== type);
+        var index = this._gutters.indexOf(type);
+        if (index === -1)
+            return;
+        this._gutters.splice(index,1);
         this.codeMirror().setOption("gutters", this._gutters.slice());
-        this.codeMirror().refresh();
+        this.refresh();
     },
 
     /**

third_party/WebKit/Source/devtools/front_end/text_editor/CodeMirrorTextEditor.js

@@ -160,6 +160,9 @@ WebInspector.CodeMirrorTextEditor = function(options)
     this.element.addEventListener("keydown", this._handleKeyDown.bind(this), true);
     this.element.addEventListener("keydown", this._handlePostKeyDown.bind(this), false);
     this.element.tabIndex = 0;
+
+    this._needsRefresh = true;
+
     if (options.mimeType)
         this.setMimeType(options.mimeType);
 }
@@ -527,10 +530,21 @@ WebInspector.CodeMirrorTextEditor.prototype = {
      */
     wasShown: function()
     {
-        if (this._wasOnceShown)
+        if (this._needsRefresh)
+            this.refresh();
+    },
+
+    /**
+     * @protected
+     */
+    refresh: function()
+    {
+        if (this.isShowing()) {
+            this._codeMirror.refresh();
+            this._needsRefresh = false;
             return;
-        this._wasOnceShown = true;
-        this._codeMirror.refresh();
+        }
+        this._needsRefresh = true;
     },
 
     /**