Fix traced StyleResolverStats

Fix traced StyleResolverStats

In r197513[1] we changed to pass a RefPtr<TracedValue> to a TRACE_EVENT macro, but
this resulted in tracing coercion to bool. This patch reverts to using PassRefPtr
but makes which macro we use conditional on whether we have a second argument.

[1] https://codereview.chromium.org/1199563003/

BUG=501634
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=197882

[dstockwell, 2015-06-25 05:59:24]

dstockwell@chromium.org changed reviewers:
+ esprehn@chromium.org, ojan@chromium.org, oysteine@chromium.org

[dstockwell, 2015-06-25 06:03:14]

Open to better ideas. I tried to pass counters.release() but the trace macros do
not expect a null PassRefPtr. @oysteine, is this something you wanted to clean
up further in TraceEvent.h?

[oystein (OOO til 10th of July), 2015-06-26 02:01:52]

lgtm

Yeah I have some thoughts on how to make TraceValues safer, but that's a
longer-term fix and shouldn't hold up this one.

[dstockwell, 2015-06-26 02:28:23]

The CQ bit was checked by dstockwell@chromium.org

[commit-bot: I haz the power, 2015-06-26 02:28:37]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1211753002/1

[commit-bot: I haz the power, 2015-06-26 03:25:04]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=197882