DevTools: Don't stop debugger inside V8 internal scripts with empty stack trace.

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

 var initialize_DebuggerTest = function() {
 
 InspectorTest.startDebuggerTest = function(callback, quiet)
 {
     console.assert(WebInspector.debuggerModel.debuggerEnabled(), "Debugger has to be enabled");
     if (quiet !== undefined)
         InspectorTest._quiet = quiet;
     WebInspector.inspectorView.showPanel("sources");
 
     InspectorTest.addSniffer(WebInspector.debuggerModel, "_pausedScript", InspectorTest._pausedScript, true);
@@ skipping 141 matching lines @@
         InspectorTest.addResult(caption);
         InspectorTest.runAfterPendingDispatches(step2);
     }
 
     function step2()
     {
         InspectorTest.resumeExecution(InspectorTest.safeWrap(callback));
     }
 };
 
+InspectorTest.waitUntilPausedAndPerformSteppingActions = function(actions, callback)
+{
+    callback = InspectorTest.safeWrap(callback);
+    InspectorTest.waitUntilPaused(didPause);
+
+    function didPause(callFrames, reason, breakpointIds, asyncStackTrace)
+    {
+        var action = actions.shift();
+        if (action === "Print") {
+            InspectorTest.captureStackTrace(callFrames, asyncStackTrace);
+            InspectorTest.addResult("");
+            while (action === "Print")
+                action = actions.shift();
+        }
+
+        if (!action) {
+            callback()
+            return;
+        }
+
+        InspectorTest.addResult("Executing " + action + "...");
+
+        switch (action) {
+        case "StepInto":
+            WebInspector.panels.sources._stepIntoButton.element.click();
+            break;
+        case "StepOver":
+            WebInspector.panels.sources._stepOverButton.element.click();
+            break;
+        case "StepOut":
+            WebInspector.panels.sources._stepOutButton.element.click();
+            break;
+        case "Resume":
+            WebInspector.panels.sources.togglePause();
+            break;
+        default:
+            InspectorTest.addResult("FAIL: Unknown action: " + action);
+            callback()
+            return;
+        }
+
+        InspectorTest.waitUntilResumed(InspectorTest.waitUntilPaused.bind(InspectorTest, didPause));
+    }
+};
+
 InspectorTest.captureStackTrace = function(callFrames, asyncStackTrace, options)
 {
     InspectorTest.addResult(InspectorTest.captureStackTraceIntoString(callFrames, asyncStackTrace, options));
 };
 
 InspectorTest.captureStackTraceIntoString = function(callFrames, asyncStackTrace, options)
 {
     var results = [];
     options = options || {};
 
@@ skipping 236 matching lines @@
 InspectorTest.scriptFormatter = function()
 {
     var editorActions = WebInspector.moduleManager.instances(WebInspector.SourcesView.EditorAction);
     for (var i = 0; i < editorActions.length; ++i) {
         if (editorActions[i] instanceof WebInspector.ScriptFormatterEditorAction)
             return editorActions[i];
     }
 };
 
 };