DevTools: Support timeline JS sampling for all threads.

Source/devtools/front_end/timeline/TracingModel.js

Index: Source/devtools/front_end/timeline/TracingModel.js
diff --git a/Source/devtools/front_end/timeline/TracingModel.js b/Source/devtools/front_end/timeline/TracingModel.js
index 4877ded527be345efa1d48a2b9f1832427c6cdf8..005ce141f06d6ea328faf977ae425b5f392ecab7 100644
--- a/Source/devtools/front_end/timeline/TracingModel.js
+++ b/Source/devtools/front_end/timeline/TracingModel.js
@@ -808,7 +808,7 @@ WebInspector.TracingModel.Thread.prototype = {
     target: function()
     {
         //FIXME: correctly specify target

[yurys, 2014/11/11 10:37:32]

We should add a test for the cpu profiler integration into timeline after target
accessor is fixed.

[alph, 2014/11/11 10:59:26]

Acknowledged.

-        return WebInspector.targetManager.targets()[0] || null;
+        return this.name() === "CrRendererMain" ? WebInspector.targetManager.targets()[0] || null : null;

[yurys, 2014/11/11 10:37:32]

if (this.name() === "CrRendererMain")
    return WebInspector.targetManager.targets()[0] || null;
return null;

[alph, 2014/11/11 10:59:26]

Done.

     },
 
     /**