Remove references to isBackground

There use to be isBackground field on Timeline events but it has been removed.

BUG=None

Review URL: https://codereview.chromium.org/334743008

git-svn-id: svn://svn.chromium.org/blink/trunk@176223 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/LayoutTests/http/tests/inspector/timeline-test.js

@@ -285,7 +285,7 @@ InspectorTest.FakeFileReader = function(input, delegate, callback)
 
 InspectorTest.dumpFrame = function(frame)
 {
-    var fieldsToDump = ["cpuTime", "duration", "startTime", "endTime", "id", "mainThreadFrameId", "isBackground", "timeByCategory", "other", "scripting", "painting", "rendering", "committedFrom"];
+    var fieldsToDump = ["cpuTime", "duration", "startTime", "endTime", "id", "mainThreadFrameId", "timeByCategory", "other", "scripting", "painting", "rendering", "committedFrom"];
     function formatFields(object)
     {
         var result = {};

third_party/WebKit/LayoutTests/inspector/timeline/timeline-network-resource.html

@@ -46,7 +46,7 @@ function test()
             else if (record.type() === WebInspector.TimelineModel.RecordType.ResourceFinish)
                 printFinish(record._record);
 
-            if (record.parent && record.parent.type() === WebInspector.TimelineModel.RecordType.Root && !record.isBackground) {
+            if (record.parent && record.parent.type() === WebInspector.TimelineModel.RecordType.Root) {
                 if (lastRecordStartTime)
                     InspectorTest.assertGreaterOrEqual(record.startTime(), lastRecordStartTime, "Top level records order violation");
                 lastRecordStartTime = record.startTime();