Web Animations API: Load resources referenced in element.animate() (reland)

Web Animations API: Load resources referenced in element.animate()

This patch fixes a bug where resources in element.animate() calls were
not being fetched. This resulted in StylePendingImages leaking out of
the style resolving stage and into rendering which causes a crash.

This patch fixes the bug by ensuring StylePendingImages introduced in
applyAnimatedProperties() will be resolved as non-pending StyleImages
through an additional call to loadPendingResources().
This patch also modifies AnimatableImage to be a wrapper of CSSValues
instead of StyleImages in order to follow the same resource caching
logic as typical CSS image values.
This patch also updates EffectInput::convert() to pass the document's
StyleSheetContents to MutableStylePropertySet::setProperty() so that
relative URLs are correctly resolved to absolute URLs.

This is a reland of https://codereview.chromium.org/196573030/ with
AnimatableImage::create() rewritten to not require an ASSERT.

BUG=353385
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=169607

[dstockwell, 2014-03-20 00:27:03]

> This is a reland of https://codereview.chromium.org/196573030/ with
AnimatableImage::create() rewritten to not require an ASSERT.

Was the ASSERT just invalid, or did something else change? Not easy to see here.

[alancutter (OOO until 2018), 2014-03-20 00:34:00]

On 2014/03/20 00:27:03, dstockwell wrote:
> > This is a reland of https://codereview.chromium.org/196573030/ with
> AnimatableImage::create() rewritten to not require an ASSERT.
> 
> Was the ASSERT just invalid, or did something else change? Not easy to see
here.

The assert was clumsily checking that the CSSValue given actually represented an
image and most likely missed a valid CSSValue type that was not obvious to me at
the time.
Instead of asserting on CSSValue types AnimatableImage::create() now just takes
a StyleImage and pulls the CSSValue off that. I think this approach is more
robust than reimplementing what it means to be an "image" type of CSSValue.

[dstockwell, 2014-03-20 00:36:25]

lgtm

[commit-bot: I haz the power, 2014-03-20 00:36:28]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/alancutter@chromium.org/196943029/1

[commit-bot: I haz the power, 2014-03-20 03:55:54]

Change committed as 169607