Rewrite svg/dynamic-updates to use text-based repaint harness

Rewrite svg/dynamic-updates to use text-based repaint harness

These tests are covering three things:

1.) Verifying that property updates are reflected through the SVG DOM API
correctly, tested via javascript

2.) Verifying that the rendering of the SVG is correct

3.) Verifying that the dynamic update of the property generates invalidations
sufficient to cover the changed area

The pixel-based repaint harness doesn't effectively handle (3) since adding the
text to the page for (1) generates lots of invalidations that are unioned with the
invalidations from the SVG itself, leading to a repaint that covers all of the SVG
and all of the text.  Additionally since these tests are all pixel tests to cover (2)
but contain lots of visible text to handle (1), the results are platform-specific due
to text rendering differences even when the SVG itself renders identically.

This converts the tests over to using the text based repaint harness to capture
invalidations to handle (3), hiding the text in the pixel output to handle (1), and
having only the SVG itself show up in the pixel output to handle (2).  Each test has
two outputs - pixel and text.  The pixel output is just the rendering of the final SVG
scene.  The text output has the contents of the JS test harness assertions from (1) and
the text representations of repaint rects generated by the SVG property updates to handle
(3).  To prevent the text output from generating invalidations that would get mixed up with
invalidations on the SVG itself, all text content is set to display:none during the test
itself by SVGTestCase.js.  At the end of the test, after the text repaint harness is told
to stop tracking invalidations, these elements are switched to being just opacity:0 so that
they still appear in the text output but do not appear in the pixel output.

BUG=344774
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=167551

[jamesr, 2014-02-19 21:39:44]

I think this ends up being a strict improvement in these tests regardless of the
status of repaint tests, which is nice.  The important changes are in
SVGTestCase.js and text-based-repaint.js.  I'm not super thrilled with injecting
a stylesheet via script, but currently ever test references SVGTestCase.js and
adding <style> would be very slightly more work.  I could do that with a small
python script if reviewers prefer.

[jamesr, 2014-02-19 21:40:17]

https://codereview.chromium.org/172973002/diff/1/LayoutTests/svg/dynamic-upda...
File LayoutTests/svg/dynamic-updates/resources/SVGTestCase.js (right):

https://codereview.chromium.org/172973002/diff/1/LayoutTests/svg/dynamic-upda...
LayoutTests/svg/dynamic-updates/resources/SVGTestCase.js:17:
document.head.parentNode.classList.add("running");
dumb question: is there a better way to refer to the HTML element?

[jamesr, 2014-02-20 19:18:53]

Anybody interested in reviewing this lovely patch?  The changes in
text-based-repaint.js and SVGTestCase.js are the only real changes, the changes
in the rest of the files are of the form s/repaint.js/text-based-repaint.js/

[pdr., 2014-02-20 19:28:29]

On 2014/02/20 19:18:53, jamesr wrote:
> Anybody interested in reviewing this lovely patch?  The changes in
> text-based-repaint.js and SVGTestCase.js are the only real changes, the
changes
> in the rest of the files are of the form s/repaint.js/text-based-repaint.js/

Lovely LGTM.

[jamesr, 2014-02-20 22:59:23]

The CQ bit was checked by jamesr@chromium.org

[commit-bot: I haz the power, 2014-02-20 22:59:34]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/jamesr@chromium.org/172973002/270002

[jamesr, 2014-02-20 23:00:24]

The CQ bit was checked by jamesr@chromium.org

[commit-bot: I haz the power, 2014-02-20 23:02:34]

Failed to trigger a try job on blink_presubmit
HTTP Error 400: Bad Request

[commit-bot: I haz the power, 2014-02-20 23:03:35]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/jamesr@chromium.org/172973002/330001

[commit-bot: I haz the power, 2014-02-21 00:45:41]

Change committed as 167551