DevTools: Adjust bad frames color on timeline flamechart.

Source/devtools/front_end/timeline/TimelineFrameModel.js

Index: Source/devtools/front_end/timeline/TimelineFrameModel.js
diff --git a/Source/devtools/front_end/timeline/TimelineFrameModel.js b/Source/devtools/front_end/timeline/TimelineFrameModel.js
index c23f1b1ed31c7feb31c7317283d5b68d9efeaea5..2ee01fef79a80d80cd16351af33bebff78e7953d 100644
--- a/Source/devtools/front_end/timeline/TimelineFrameModel.js
+++ b/Source/devtools/front_end/timeline/TimelineFrameModel.js
@@ -572,6 +572,15 @@ WebInspector.TimelineFrame = function(startTime, startTimeOffset)
 
 WebInspector.TimelineFrame.prototype = {
     /**
+     * @return {boolean}
+     */
+    hasWarnings: function()
+    {
+        var /** @const */ longFrameDurationThresholdMs = 18;
+        return !this.idle && this.duration > longFrameDurationThresholdMs;
+    },
+
+    /**
      * @param {number} endTime
      */
     _setEndTime: function(endTime)