Tests asynchronous call stacks for XHRs.

Set timer for test function.
Captured call stacks in no particular order:
Call stack:
    0) downloadEnd1 (async-callstack-xhrs.js:41)
    1) sendXHR (async-callstack-xhrs.js:71)
    2) sendSyncXHR (async-callstack-xhrs.js:26)
    3) timeout (async-callstack-xhrs.js:21)
    [setTimeout]
    0) testFunction (async-callstack-xhrs.js:16)
    [setTimeout]
    0) scheduleTestFunction <omitted>
    <... skipped remaining frames ...>

Call stack:
    0) downloadEnd1 (async-callstack-xhrs.js:41)
    [XMLHttpRequest.send]
    0) sendXHR (async-callstack-xhrs.js:71)
    1) sendAsyncXHR (async-callstack-xhrs.js:25)
    2) timeout (async-callstack-xhrs.js:22)
    [setTimeout]
    0) testFunction (async-callstack-xhrs.js:16)
    [setTimeout]
    0) scheduleTestFunction <omitted>
    <... skipped remaining frames ...>

Call stack:
    0) downloadEnd2 (async-callstack-xhrs.js:46)
    1) sendXHR (async-callstack-xhrs.js:71)
    2) sendSyncXHR (async-callstack-xhrs.js:26)
    3) timeout (async-callstack-xhrs.js:21)
    [setTimeout]
    0) testFunction (async-callstack-xhrs.js:16)
    [setTimeout]
    0) scheduleTestFunction <omitted>
    <... skipped remaining frames ...>

Call stack:
    0) downloadEnd2 (async-callstack-xhrs.js:46)
    [XMLHttpRequest.send]
    0) sendXHR (async-callstack-xhrs.js:71)
    1) sendAsyncXHR (async-callstack-xhrs.js:25)
    2) timeout (async-callstack-xhrs.js:22)
    [setTimeout]
    0) testFunction (async-callstack-xhrs.js:16)
    [setTimeout]
    0) scheduleTestFunction <omitted>
    <... skipped remaining frames ...>

Call stack:
    0) downloadProgress (async-callstack-xhrs.js:55)
    [XMLHttpRequest.send]
    0) sendXHR (async-callstack-xhrs.js:71)
    1) sendAsyncXHR (async-callstack-xhrs.js:25)
    2) timeout (async-callstack-xhrs.js:22)
    [setTimeout]
    0) testFunction (async-callstack-xhrs.js:16)
    [setTimeout]
    0) scheduleTestFunction <omitted>
    <... skipped remaining frames ...>

Call stack:
    0) uploadEnd (async-callstack-xhrs.js:51)
    [XMLHttpRequest.send]
    0) sendXHR (async-callstack-xhrs.js:71)
    1) sendAsyncXHR (async-callstack-xhrs.js:25)
    2) timeout (async-callstack-xhrs.js:22)
    [setTimeout]
    0) testFunction (async-callstack-xhrs.js:16)
    [setTimeout]
    0) scheduleTestFunction <omitted>
    <... skipped remaining frames ...>

Call stack:
    0) uploadProgress (async-callstack-xhrs.js:60)
    [XMLHttpRequest.send]
    0) sendXHR (async-callstack-xhrs.js:71)
    1) sendAsyncXHR (async-callstack-xhrs.js:25)
    2) timeout (async-callstack-xhrs.js:22)
    [setTimeout]
    0) testFunction (async-callstack-xhrs.js:16)
    [setTimeout]
    0) scheduleTestFunction <omitted>
    <... skipped remaining frames ...>

Call stack:
    0) xhr.onreadystatechange (async-callstack-xhrs.js:35)
    1) sendXHR (async-callstack-xhrs.js:71)
    2) sendSyncXHR (async-callstack-xhrs.js:26)
    3) timeout (async-callstack-xhrs.js:21)
    [setTimeout]
    0) testFunction (async-callstack-xhrs.js:16)
    [setTimeout]
    0) scheduleTestFunction <omitted>
    <... skipped remaining frames ...>

Call stack:
    0) xhr.onreadystatechange (async-callstack-xhrs.js:35)
    [XMLHttpRequest.send]
    0) sendXHR (async-callstack-xhrs.js:71)
    1) sendAsyncXHR (async-callstack-xhrs.js:25)
    2) timeout (async-callstack-xhrs.js:22)
    [setTimeout]
    0) testFunction (async-callstack-xhrs.js:16)
    [setTimeout]
    0) scheduleTestFunction <omitted>
    <... skipped remaining frames ...>