DO NOT LAND - Code for debugging excess style recalcs

DO NOT LAND - Code for debugging excess style recalcs

Ideally the inspector could surface something like this.

This printf is fantastically useful for understanding where
large style invalidations are coming from.  Saving it off in a CL
for future use.

BUG=316388, 325900

[eseidel, 2013-11-07 00:07:03]

Others may find this useful some day.

[eseidel, 2013-11-07 02:50:28]

I should figure out how to print the current v8 stack and then this might be
really useful to web devs.

[eseidel, 2013-11-08 10:32:39]

Filed bug 316388 about making a shipable version of this.

[eseidel, 2013-12-04 21:56:34]

Filed issue 325900 about exposing something like this in the inspector.

[eseidel, 2014-04-21 18:05:34]

This was landed as style.debug in about:tracing.

[pfeldman, 2014-04-22 05:55:50]

On 2014/04/21 18:05:34, eseidel wrote:
> This was landed as style.debug in about:tracing.

[+yurys] Lets update it with the generic stack convertable-to-tracing once it is
there. We probably want to make this converter public and accessible from
anywhere in core/.

[esprehn, 2014-04-22 05:56:33]

On 2014/04/22 05:55:50, pfeldman wrote:
> On 2014/04/21 18:05:34, eseidel wrote:
> > This was landed as style.debug in about:tracing.
> 
> [+yurys] Lets update it with the generic stack convertable-to-tracing once it
is
> there. We probably want to make this converter public and accessible from
> anywhere in core/.

Note that this does terrible things for performance, so it needs to be an opt in
only when you want to see the recalc tree sizes.

[eseidel, 2014-04-22 06:26:53]

style.debug is super-useful and I hope we'll show that information in the
inspector soon.   As elliot says, it only makes sense in some sort of
"performance audit" mode, but highlighting large style invalidations has been
really helpful for tracking down performance mistakes in google apps.