DevTools: remove nesting depth tracking from coverage

third_party/WebKit/Source/devtools/front_end/coverage/CoverageView.js

 // Copyright (c) 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 Coverage.CoverageView = class extends UI.VBox {
   constructor() {
     super(true);
 
     /** @type {?Coverage.CoverageModel} */
     this._model = null;
@@ skipping 115 matching lines @@
    */
   decorate(uiSourceCode, textEditor) {
     var gutterType = 'CodeMirror-gutter-coverage';
 
     var decorations = uiSourceCode.decorationsForType(Coverage.CoverageView.LineDecorator.type);
     textEditor.uninstallGutter(gutterType);
     if (!decorations || !decorations.size)
       return;
 
     textEditor.installGutter(gutterType, false);
-
+    var lastLine = 0;
+    var lastData = undefined;
     for (var decoration of decorations) {
-      for (var line = decoration.range().startLine; line <= decoration.range().endLine; ++line) {
-        var element = createElementWithClass('div');
-        if (decoration.data())
-          element.className = 'text-editor-coverage-used-marker';
-        else
-          element.className = 'text-editor-coverage-unused-marker';
-
+      var range = decoration.range();
+      var startLine = range.startLine;
+      if (lastLine && lastLine === startLine && lastData !== !!decoration.data()) {

[alph, 2017/03/22 22:30:58]

nit: drop "lastLine &&"

+        var element = createElementWithClass('div', 'text-editor-coverage-mixed-marker');
+        textEditor.setGutterDecoration(startLine, gutterType, element);
+        startLine++;
+      } else {
+        startLine = Math.max(startLine, lastLine);
+      }
+      lastLine = range.endLine;
+      lastData = !!decoration.data();
+      var className = lastData ? 'text-editor-coverage-used-marker' : 'text-editor-coverage-unused-marker';
+      for (var line = startLine; line <= lastLine; ++line) {
+        var element = createElementWithClass('div', className);
         textEditor.setGutterDecoration(line, gutterType, element);
       }
     }
   }
 };
 
 Coverage.CoverageView.LineDecorator.type = 'coverage';
 
 /**
  * @implements {UI.ActionDelegate}
  */
 Coverage.CoverageView.RecordActionDelegate = class {
   /**
    * @override
    * @param {!UI.Context} context
    * @param {string} actionId
    * @return {boolean}
    */
   handleAction(context, actionId) {
     var coverageViewId = 'coverage';
     UI.viewManager.showView(coverageViewId)
         .then(() => UI.viewManager.view(coverageViewId).widget())
         .then(widget => /** @type !Coverage.CoverageView} */ (widget)._toggleRecording());
 
     return true;
   }
 };