DevTools: Support XHR async call stacks in the debugger.

LayoutTests/http/tests/inspector/inspector-test.js

 var initialize_InspectorTest = function() {
 
 var results = [];
 var resultsSynchronized = false;
 
 function consoleOutputHook(messageType)
 {
     InspectorTest.addResult(messageType + ": " + Array.prototype.slice.call(arguments, 1));
 }
 
@@ skipping 83 matching lines @@
 }
 
 InspectorTest.check = function(passCondition, failureText)
 {
     if (!passCondition)
         InspectorTest.addResult("FAIL: " + failureText);
 }
 
 InspectorTest.addResult = function(text)
 {
-    if (InspectorTest._resultBufferring) {
-        InspectorTest._resultBufferringContent += text + "\n";
-        return;
-    }
     results.push(text);
     if (resultsSynchronized)
         InspectorTest.Output.addResult(text);
     else {
         InspectorTest.Output.clearResults();
         for (var i = 0; i < results.length; ++i)
             InspectorTest.Output.addResult(results[i]);
         resultsSynchronized = true;
     }
 }
 
-InspectorTest.beginResultBufferring = function()
-{
-    InspectorTest._resultBufferring = true;
-    InspectorTest._resultBufferringContent = "";
-}
-
-InspectorTest.endResultBufferring = function()
-{
-    var result = InspectorTest._resultBufferringContent || "";
-    delete InspectorTest._resultBufferring;
-    delete InspectorTest._resultBufferringContent;
-    return result;
-}
-
 InspectorTest.addResults = function(textArray)
 {
     if (!textArray)
         return;
     for (var i = 0, size = textArray.length; i < size; ++i)
         InspectorTest.addResult(textArray[i]);
 }
 
 function onError(event)
 {
@@ skipping 516 matching lines @@
     evaluateInWebInspector: function(callId, script)
     {
         window.opener.postMessage(["evaluateInWebInspector", callId, script], "*");
     },
 
     display: function() { }
 }
 
 if (!window.testRunner && window.opener)
     window.testRunner = new StandaloneTestRunnerStub();