Avoid scaling a zero-sized image

Avoid scaling a zero-sized image

Since scaling a zero-sized image can result in dealing with NaNs (in case
that we're scaling it using an inf, which is fairly possible), we should
avoid doing that. This CL makes sure that we do.

As to why we're dealing with zero sized images to begin with, I've opened
crbug.com/522637, but it seems like something that can happen regardless,
when ImageResource doesn't have an Image.

BUG=521954
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=200879

[Yoav Weiss, 2015-08-19 22:04:37]

yoav@yoav.ws changed reviewers:
+ pdr@chromium.org

[Yoav Weiss, 2015-08-19 22:04:38]

Hey Philip :)

Can you please take a look? This CL makes sure that even when we have zero sized
images, our scaling doesn't blow up in our faces due to NaNs. I've opened a
separate issue to make sure that the test scenario that caught this won't have a
zero sized images (since it shouldn't).

[Yoav Weiss, 2015-08-19 22:09:57]

https://codereview.chromium.org/1299493005/diff/20001/LayoutTests/imported/we...
File
LayoutTests/imported/web-platform-tests/html/semantics/embedded-content/the-img-element/srcset/parse-a-srcset-attribute-expected.txt
(right):

https://codereview.chromium.org/1299493005/diff/20001/LayoutTests/imported/we...
LayoutTests/imported/web-platform-tests/html/semantics/embedded-content/the-img-element/srcset/parse-a-srcset-attribute-expected.txt:528:
FAIL "data:,a 1.x" assert_equals: expected "" but got "data:,a"
This failure is due to the fact that "1." is something we consider a legit
float, contrary to the spec.
I've tried to fix that in the past, but a bunch of tests failed as a result.

[jsbell, 2015-08-19 22:22:30]

jsbell@chromium.org changed reviewers:
+ jsbell@chromium.org

[jsbell, 2015-08-19 22:22:31]

drive-by lgtm on the imported/web-platform-test changes

[pdr., 2015-08-20 05:22:21]

LGTM

[Yoav Weiss, 2015-08-20 05:34:23]

The CQ bit was checked by yoav@yoav.ws

[commit-bot: I haz the power, 2015-08-20 05:34:35]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1299493005/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1299493005/20001

[commit-bot: I haz the power, 2015-08-20 06:38:32]

Committed patchset #2 (id:20001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=200879