DevTools: Add JSDoc for static methods, fix JSDoc types and induced errors

Source/devtools/front_end/timeline/TimelineUIUtils.js

Index: Source/devtools/front_end/timeline/TimelineUIUtils.js
diff --git a/Source/devtools/front_end/timeline/TimelineUIUtils.js b/Source/devtools/front_end/timeline/TimelineUIUtils.js
index 1663aa5872bdb9eb000557a0c980c5d3c8d99406..3c53b85fc5acb98433ac6ae4aef76fabc45dc6d1 100644
--- a/Source/devtools/front_end/timeline/TimelineUIUtils.js
+++ b/Source/devtools/front_end/timeline/TimelineUIUtils.js
@@ -33,6 +33,9 @@
  */
 WebInspector.TimelineUIUtils = function() { }
 
+/**
+ * @return {!Object.<string, !WebInspector.TimelineCategory>}
+ */
 WebInspector.TimelineUIUtils.categories = function()
 {
     if (WebInspector.TimelineUIUtils._categories)
@@ -147,6 +150,7 @@ WebInspector.TimelineUIUtils.categoryForRecord = function(record)
 
 /**
  * @param {!WebInspector.TimelineModel.Record} record
+ * @return {boolean}
  */
 WebInspector.TimelineUIUtils.isEventDivider = function(record)
 {
@@ -183,6 +187,7 @@ WebInspector.TimelineUIUtils.needsPreviewElement = function(recordType)
 /**
  * @param {string} recordType
  * @param {string=} title
+ * @return {!Element}
  */
 WebInspector.TimelineUIUtils.createEventDivider = function(recordType, title)
 {
@@ -363,6 +368,7 @@ WebInspector.TimelineUIUtils.generatePieChart = function(aggregatedStats, selfCa
 /**
  * @param {!WebInspector.TimelineFrameModel} frameModel
  * @param {!WebInspector.TimelineFrame} frame
+ * @return {!Element}
  */
 WebInspector.TimelineUIUtils.generatePopupContentForFrame = function(frameModel, frame)
 {
@@ -384,6 +390,7 @@ WebInspector.TimelineUIUtils.generatePopupContentForFrame = function(frameModel,
 
 /**
  * @param {!WebInspector.FrameStatistics} statistics
+ * @return {!Element}
  */
 WebInspector.TimelineUIUtils.generatePopupContentForFrameStatistics = function(statistics)
 {
@@ -411,6 +418,7 @@ WebInspector.TimelineUIUtils.generatePopupContentForFrameStatistics = function(s
  * @param {string} color0
  * @param {string} color1
  * @param {string} color2
+ * @return {!CanvasGradient}
  */
 WebInspector.TimelineUIUtils.createFillStyle = function(context, width, height, color0, color1, color2)
 {
@@ -427,6 +435,7 @@ WebInspector.TimelineUIUtils.createFillStyle = function(context, width, height,
  * @param {number} width
  * @param {number} height
  * @param {!WebInspector.TimelineCategory} category
+ * @return {!CanvasGradient}
  */
 WebInspector.TimelineUIUtils.createFillStyleForCategory = function(context, width, height, category)
 {
@@ -435,6 +444,7 @@ WebInspector.TimelineUIUtils.createFillStyleForCategory = function(context, widt
 
 /**
  * @param {!WebInspector.TimelineCategory} category
+ * @return {string}
  */
 WebInspector.TimelineUIUtils.createStyleRuleForCategory = function(category)
 {