DevTools: Display function names instead of general "[Async Call]".

Display async call function's name, like setTimeout or requestAnimationFrame.

BUG=272416
R=pfeldman

Review URL: https://codereview.chromium.org/106973009

git-svn-id: svn://svn.chromium.org/blink/trunk@163561 bbb929c8-8fbe-4397-9dbb-9b2b20218538