Disable canvas line dashing when dash sequence is all zeros.

Disable canvas line dashing when dash sequence is all zeros.

BUG=535281
R=senorblanco@chromium.org

Committed: https://crrev.com/1c577f8478cf5d72b9b155c8bdccd0a246da5130
Cr-Commit-Position: refs/heads/master@{#351833}

[Justin Novosad, 2015-10-01 15:27:45]

PTAL

[Stephen White, 2015-10-01 15:46:02]

https://codereview.chromium.org/1381973002/diff/1/third_party/WebKit/LayoutTe...
File third_party/WebKit/LayoutTests/fast/canvas/script-tests/canvas-lineDash.js
(right):

https://codereview.chromium.org/1381973002/diff/1/third_party/WebKit/LayoutTe...
third_party/WebKit/LayoutTests/fast/canvas/script-tests/canvas-lineDash.js:108:
ctx.setLineDash([0, 0]);
Please add a [null, null] case as well, since it's closer to the original bug.

https://codereview.chromium.org/1381973002/diff/1/third_party/WebKit/Source/m...
File
third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2DState.cpp
(right):

https://codereview.chromium.org/1381973002/diff/1/third_party/WebKit/Source/m...
third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2DState.cpp:216:
if (!hasANonZeroElement(m_lineDash)) {
Please create a Skia bug for this (diff between hw & sw rendering in this case),
and mention that this workaround could be removed when the Skia bug is fixed.

[Justin Novosad, 2015-10-01 16:06:42]

https://codereview.chromium.org/1381973002/diff/1/third_party/WebKit/LayoutTe...
File third_party/WebKit/LayoutTests/fast/canvas/script-tests/canvas-lineDash.js
(right):

https://codereview.chromium.org/1381973002/diff/1/third_party/WebKit/LayoutTe...
third_party/WebKit/LayoutTests/fast/canvas/script-tests/canvas-lineDash.js:108:
ctx.setLineDash([0, 0]);
On 2015/10/01 15:46:02, Stephen White wrote:
> Please add a [null, null] case as well, since it's closer to the original bug.

Done.

https://codereview.chromium.org/1381973002/diff/1/third_party/WebKit/Source/m...
File
third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2DState.cpp
(right):

https://codereview.chromium.org/1381973002/diff/1/third_party/WebKit/Source/m...
third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2DState.cpp:216:
if (!hasANonZeroElement(m_lineDash)) {
On 2015/10/01 15:46:02, Stephen White wrote:
> Please create a Skia bug for this (diff between hw & sw rendering in this
case),
> and mention that this workaround could be removed when the Skia bug is fixed.

I'll create a skia bug, but I don't think this workaround should be removed
since there is no point in create a no-op path effect.

[Stephen White, 2015-10-01 16:54:44]

LGTM

https://codereview.chromium.org/1381973002/diff/1/third_party/WebKit/Source/m...
File
third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2DState.cpp
(right):

https://codereview.chromium.org/1381973002/diff/1/third_party/WebKit/Source/m...
third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2DState.cpp:216:
if (!hasANonZeroElement(m_lineDash)) {
On 2015/10/01 16:06:42, Justin Novosad wrote:
> On 2015/10/01 15:46:02, Stephen White wrote:
> > Please create a Skia bug for this (diff between hw & sw rendering in this
> case),
> > and mention that this workaround could be removed when the Skia bug is
fixed.
> 
> I'll create a skia bug, but I don't think this workaround should be removed
> since there is no point in create a no-op path effect.

Acknowledged.

[Justin Novosad, 2015-10-01 16:55:30]

The CQ bit was checked by junov@chromium.org

[commit-bot: I haz the power, 2015-10-01 16:55:48]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1381973002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1381973002/20001

[commit-bot: I haz the power, 2015-10-01 17:29:55]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-10-01 17:32:01]

Patchset 2 (id:??) landed as
https://crrev.com/1c577f8478cf5d72b9b155c8bdccd0a246da5130
Cr-Commit-Position: refs/heads/master@{#351833}