DevTools: Switch to using fast stack iterator to collect stacks during timeline recording.

third_party/WebKit/LayoutTests/inspector/tracing/timeline-animation-frame-expected.txt

 Tests the Timeline events for Animation Frame feature
 
 RequestAnimationFrame Properties:
 {
     data : {
         frame : <string>
         id : <number>
         stackTrace : <object>
     }
     endTime : <number>
     frameId : <string>
     stackTrace : <object>
     startTime : <number>
     type : "RequestAnimationFrame"
 }
-Text details for RequestAnimationFrame: timeline-animation-frame.html:8
+Text details for RequestAnimationFrame: null

[caseq, 2016/01/25 19:18:36]

why is this gone?

[alph, 2016/01/26 00:58:49]

That's because it's now collects systems frames as well, so the system frame is
the function of requestAnimationFrame which url is missing.
Fixed that.

 FireAnimationFrame Properties:
 {
     data : {
         frame : <string>
         id : <number>
     }
     endTime : <number>
     frameId : <string>
     startTime : <number>
     type : "FireAnimationFrame"
 }
-Text details for FireAnimationFrame: timeline-animation-frame.html:8
+Text details for FireAnimationFrame: null
 CancelAnimationFrame Properties:
 {
     data : {
         frame : <string>
         id : <number>
         stackTrace : <object>
     }
     endTime : <number>
     frameId : <string>
     stackTrace : <object>
     startTime : <number>
     type : "CancelAnimationFrame"
 }
-Text details for CancelAnimationFrame: timeline-animation-frame.html:11
+Text details for CancelAnimationFrame: null