HTMLImageElement: do not use fallback content for ImageDocument

HTMLImageElement: do not use fallback content for ImageDocument

After https://codereview.chromium.org/1879793003,
ImageLoader::hasPendingActivity() became false for ImageDocument and thus
HTMLImageElement::selectSourceURL() didn't consider the image as still loading
during load (|imageStillLoading| became false).
This caused ImageDocument not to be displayed progressively.

This CL makes HTMLImageElement to use primary content for ImageDocument.
This causes ImageDocument not to be replaced with fallback content, but I
expect that is more acceptable than images not displayed progressively.

BUG=632495
Review-Url: https://codereview.chromium.org/2343613002
Cr-Commit-Position: refs/heads/master@{#420432}
(cherry picked from commit c5e43f7edf4e55155fcda51be0285f37b20c2e76)

Committed: https://chromium.googlesource.com/chromium/src/+/01e1c1571cd16ec4f3ff0342f8f1e0f943cd942f

[hiroshige, 2016-09-26 05:16:35]

Description was changed from

==========
HTMLImageElement: do not use fallback content for ImageDocument

After https://codereview.chromium.org/1879793003,
ImageLoader::hasPendingActivity() became false for ImageDocument and thus
HTMLImageElement::selectSourceURL() didn't consider the image as still loading
during load (|imageStillLoading| became false).
This caused ImageDocument not to be displayed progressively.

This CL makes HTMLImageElement to use primary content for ImageDocument.
This causes ImageDocument not to be replaced with fallback content, but I
expect that is more acceptable than images not displayed progressively.

BUG=632495

Review-Url: https://codereview.chromium.org/2343613002
Cr-Commit-Position: refs/heads/master@{#420432}
(cherry picked from commit c5e43f7edf4e55155fcda51be0285f37b20c2e76)
==========

to

==========
HTMLImageElement: do not use fallback content for ImageDocument

After https://codereview.chromium.org/1879793003,
ImageLoader::hasPendingActivity() became false for ImageDocument and thus
HTMLImageElement::selectSourceURL() didn't consider the image as still loading
during load (|imageStillLoading| became false).
This caused ImageDocument not to be displayed progressively.

This CL makes HTMLImageElement to use primary content for ImageDocument.
This causes ImageDocument not to be replaced with fallback content, but I
expect that is more acceptable than images not displayed progressively.

BUG=632495

Review-Url: https://codereview.chromium.org/2343613002
Cr-Commit-Position: refs/heads/master@{#420432}
(cherry picked from commit c5e43f7edf4e55155fcda51be0285f37b20c2e76)

Committed:
https://chromium.googlesource.com/chromium/src/+/01e1c1571cd16ec4f3ff0342f8f1...
==========

[hiroshige, 2016-09-26 05:16:38]

Committed patchset #1 (id:1) manually as
01e1c1571cd16ec4f3ff0342f8f1e0f943cd942f.