DevTools: Show displayName in frame call stack and popovers for functions.

Drive-by: The displayName in FunctionDetails was never sent back to frontend for V8 (it was implemented for JSC only for some reason).

Next: do the same for CPU profiler results.

BUG=17356
R=yurys,pfeldman

Review URL: https://codereview.chromium.org/26121003

git-svn-id: svn://svn.chromium.org/blink/trunk@160130 bbb929c8-8fbe-4397-9dbb-9b2b20218538