Dart: Use dart:developer for tracing in startup benchmark.

Dart: Use dart:developer for tracing in startup benchmark.

BUG=
R=johnmccutchan@google.com

Committed: https://chromium.googlesource.com/external/mojo/+/653331f1044ffe38a010e6bc33450fbdc9794cc5

[zra, 2015-11-12 22:39:01]

zra@google.com changed reviewers:
+ johnmccutchan@google.com

[zra, 2015-11-12 22:39:01]

This saves another ~10+ ms.

John, it would be nice to be able to specify a category other than "Dart". Is
there some reason it has to be "Dart"? Also, compilation of the JSON encoding
for the argument Map takes ~5ms. If there was some way around that, that could
help too.

[zra, 2015-11-12 23:02:42]

Hmm. It looks like the analyzer doesn't believe that Timeline.instantSync
exists. Any ideas?

[Cutch, 2015-11-12 23:03:47]

On 2015/11/12 23:02:42, zra wrote:
> Hmm. It looks like the analyzer doesn't believe that Timeline.instantSync
> exists. Any ideas?

Roll the binary sdk forward

[zra, 2015-11-12 23:13:37]

On 2015/11/12 23:03:47, Cutch wrote:
> Roll the binary sdk forward

Ah, right. The most recent dev build doesn't include the new Timeline functions
since those are pretty recent. Rather than moving the binary SDK to something on
bleeding-edge, I think we should probably just wait for the next dev build. I'll
ping this issue when that's available.

[zra, 2015-11-19 17:40:15]

PTAL.

Will switch RTT benchmark to dart:tracing in another CL since it looks like I'll
have to plumb the flag for retaining the complete trace to make that work.

[Cutch, 2015-11-19 17:55:42]

lgtm

[zra, 2015-11-19 17:57:12]

Committed patchset #3 (id:40001) manually as
653331f1044ffe38a010e6bc33450fbdc9794cc5 (presubmit successful).