[SVG] Reinstate RenderSVGResourcePattern's inval-during-paint guard.

[SVG] Reinstate RenderSVGResourcePattern's inval-during-paint guard.

The refactoring in https://codereview.chromium.org/453653003 dropped the
double-lookup map insertion, but animated images (at least) can still
trigger paint-time layout invals => the map entry may get deleted while
we're building the pattern.

This CL adds back the required double-lookup idiom.

R=fs@opera.com,pdr@chromium.org,schenney@chromium.org
BUG=426757, 426882
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=184370

[f(malita), 2014-10-24 13:47:35]

fmalita@chromium.org changed reviewers:
+ fs@opera.com, pdr@chromium.org, schenney@chromium.org

[fs, 2014-10-24 14:39:02]

Oh, unpleasant =/. LGTM.

[fs, 2014-10-24 14:42:04]

On 2014/10/24 14:39:02, fs wrote:
> Oh, unpleasant =/. LGTM.

And, will you add the/a TC?

[f(malita), 2014-10-24 14:45:09]

On 2014/10/24 14:42:04, fs wrote:
> On 2014/10/24 14:39:02, fs wrote:
> > Oh, unpleasant =/. LGTM.
> 
> And, will you add the/a TC?

Not easily done: the trigger is racy/dependent on animation timers and I
couldn't find a way to repro in a TC :(

We (thankfully) do have CF coverage though.

[fs, 2014-10-24 14:48:31]

On 2014/10/24 14:45:09, Florin Malita wrote:
> On 2014/10/24 14:42:04, fs wrote:
> > On 2014/10/24 14:39:02, fs wrote:
> > > Oh, unpleasant =/. LGTM.
> > 
> > And, will you add the/a TC?
> 
> Not easily done: the trigger is racy/dependent on animation timers and I
> couldn't find a way to repro in a TC :(
> 
> We (thankfully) do have CF coverage though.

Ok. Maybe you could create a bug (or similar) with some extended info, so that
we can gain insight into the problem at hand?

[f(malita), 2014-10-24 15:44:49]

On 2014/10/24 14:48:31, fs wrote:
> On 2014/10/24 14:45:09, Florin Malita wrote:
> > On 2014/10/24 14:42:04, fs wrote:
> > > On 2014/10/24 14:39:02, fs wrote:
> > > > Oh, unpleasant =/. LGTM.
> > > 
> > > And, will you add the/a TC?
> > 
> > Not easily done: the trigger is racy/dependent on animation timers and I
> > couldn't find a way to repro in a TC :(
> > 
> > We (thankfully) do have CF coverage though.
> 
> Ok. Maybe you could create a bug (or similar) with some extended info, so that
> we can gain insight into the problem at hand?

Done: http://crbug.com/426882

[f(malita), 2014-10-24 16:14:17]

The CQ bit was checked by fmalita@chromium.org

[commit-bot: I haz the power, 2014-10-24 16:15:42]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/677683003/20001

[commit-bot: I haz the power, 2014-10-24 16:20:30]

Committed patchset #2 (id:20001) as 184370

[fs, 2014-10-27 09:52:37]

On 2014/10/24 15:44:49, Florin Malita wrote:
> On 2014/10/24 14:48:31, fs wrote:
> > On 2014/10/24 14:45:09, Florin Malita wrote:
> > > On 2014/10/24 14:42:04, fs wrote:
> > > > On 2014/10/24 14:39:02, fs wrote:
> > > > > Oh, unpleasant =/. LGTM.
> > > > 
> > > > And, will you add the/a TC?
> > > 
> > > Not easily done: the trigger is racy/dependent on animation timers and I
> > > couldn't find a way to repro in a TC :(
> > > 
> > > We (thankfully) do have CF coverage though.
> > 
> > Ok. Maybe you could create a bug (or similar) with some extended info, so
that
> > we can gain insight into the problem at hand?
> 
> Done: http://crbug.com/426882

Thanks.