Add UseCounter for flex items having intinsic aspect ratios

Add UseCounter for flex items having intinsic aspect ratios

According to flexbox spec http://dev.w3.org/csswg/css-flexbox/#algo-main-item
we should take intrinsic aspect ratios into account during main-size calculation.
Currently none of the browser is taking aspect ratio into account while calculating
main-size of flexbox.

Adding a use counter to determine how common it is for a flex item
to have intrinsic aspect ratios.

BUG=249112
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=177981

[harpreet.sk, 2014-07-09 12:03:26]

PTAL...

This CL has been added as per comment#9 in
https://codereview.chromium.org/343103003/
to determine how common it is for a flex item to have an intrinsic ratio.

@tony: Currently i have added the UseCounter for the case in which flex-item has
either as aspect ratio defined explicitly or is image or video or canvas. Please
let me know if you want UseCounter for image only.

[tony, 2014-07-09 16:16:51]

I'm not an OWNER of this code, but LGTM.

This will do a bit of over counting (since maybe the flex item isn't flexing),
but it seems like a reasonable start.

[harpreet.sk, 2014-07-10 06:53:03]

@leviw can you please give lgtm

[harpreet.sk, 2014-07-11 16:47:53]

Owners please give lgtm

[eseidel, 2014-07-11 19:45:56]

lgtm

[commit-bot: I haz the power, 2014-07-11 19:47:24]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/harpreet.sk@samsung.com/381613002/1

[commit-bot: I haz the power, 2014-07-11 20:57:30]

FYI, CQ is re-trying this CL (attempt #1).
The failing builders are:
  win_blink_compile_dbg on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/win_blink_compile_dbg/bu...)
  win_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/win_blink_rel/builds/16518)

[commit-bot: I haz the power, 2014-07-11 21:29:20]

Change committed as 177981