Add plumbing for font-stretch

Add plumbing for font-stretch

Implement support for parsing and querying the font-stretch CSS
property, for extracting the font-stretch from the short-hand font
property, and for querying the font-stretch through getComputedStyle.

Note that this patch does _not_ implement the font-stretch
functionality itself, it merely adds the required plumbing.

Request to implement thread:
  https://groups.google.com/a/chromium.org/forum/#!msg/blink-dev/N24I2zJemvI

Entry in Chromium Dashboard:
  http://www.chromestatus.com/features/4598830058176512

R=dglazkov@chromium.org
BUG=331119
TEST=fast/css3-text/font-stretch.html

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=169264

[dglazkov, 2014-03-13 20:42:17]

lgtm. Does this need to be behind flag for now?

[eae, 2014-03-13 21:38:00]

On 2014/03/13 20:42:17, dglazkov wrote:
> lgtm. Does this need to be behind flag for now?

It has no effect yet (other than exposing it through computed style). My plan is
to have the actual implementation behind a flag but not the plumbing as the
number of entry points would result in a lot of flag checks.

[ojan, 2014-03-13 21:53:23]

On 2014/03/13 21:38:00, eae wrote:
> On 2014/03/13 20:42:17, dglazkov wrote:
> > lgtm. Does this need to be behind flag for now?
> 
> It has no effect yet (other than exposing it through computed style). My plan
is
> to have the actual implementation behind a flag but not the plumbing as the
> number of entry points would result in a lot of flag checks.

It also exposes it on the style property on Element. The problem with this is
that it breaks feature detection. I swear we have a way to conditionalize CSS
property names on a RuntimeEnabledFeature flag, but I can't seem to find it.
Eric, do you know?

https://codereview.chromium.org/199423003/diff/1/Source/core/css/CSSShorthand...
File Source/core/css/CSSShorthands.in (right):

https://codereview.chromium.org/199423003/diff/1/Source/core/css/CSSShorthand...
Source/core/css/CSSShorthands.in:23: font
longhands=font-family;font-size;font-style;font-variant;font-weight;font-stretch;line-height
I think you can runtime control this using runtimeEnabledShorthand.

https://codereview.chromium.org/199423003/diff/1/Source/core/css/parser/CSSPr...
File Source/core/css/parser/CSSPropertyParser.cpp (right):

https://codereview.chromium.org/199423003/diff/1/Source/core/css/parser/CSSPr...
Source/core/css/parser/CSSPropertyParser.cpp:565: case CSSPropertyFontStretch: {
// normal | ultra-condensed | extra-condensed | condensed | semi-condensed |
semi-expanded | expanded | extra-expanded | ultra-expanded
I know code around this does this comment thing, but I think we should gradually
remove all these sorts of comments. They get stale quickly.

[eae, 2014-03-13 22:08:08]

On 2014/03/13 21:53:23, ojan wrote:
> On 2014/03/13 21:38:00, eae wrote:
> > On 2014/03/13 20:42:17, dglazkov wrote:
> > > lgtm. Does this need to be behind flag for now?
> > 
> > It has no effect yet (other than exposing it through computed style). My
plan
> is
> > to have the actual implementation behind a flag but not the plumbing as the
> > number of entry points would result in a lot of flag checks.
> 
> It also exposes it on the style property on Element. The problem with this is
> that it breaks feature detection. I swear we have a way to conditionalize CSS
> property names on a RuntimeEnabledFeature flag, but I can't seem to find it.
> Eric, do you know?

It is already exposed that way, "typeof document.body.style.fontStretch" returns
string in chrome going back at least a year.


>
https://codereview.chromium.org/199423003/diff/1/Source/core/css/CSSShorthand...
> File Source/core/css/CSSShorthands.in (right):
> 
>
https://codereview.chromium.org/199423003/diff/1/Source/core/css/CSSShorthand...
> Source/core/css/CSSShorthands.in:23: font
>
longhands=font-family;font-size;font-style;font-variant;font-weight;font-stretch;line-height
> I think you can runtime control this using runtimeEnabledShorthand.

I looked into that but it only seems to work for entirely new properties :(


>
https://codereview.chromium.org/199423003/diff/1/Source/core/css/parser/CSSPr...
> File Source/core/css/parser/CSSPropertyParser.cpp (right):
> 
>
https://codereview.chromium.org/199423003/diff/1/Source/core/css/parser/CSSPr...
> Source/core/css/parser/CSSPropertyParser.cpp:565: case CSSPropertyFontStretch:
{
> // normal | ultra-condensed | extra-condensed | condensed | semi-condensed |
> semi-expanded | expanded | extra-expanded | ultra-expanded
> I know code around this does this comment thing, but I think we should
gradually
> remove all these sorts of comments. They get stale quickly.

[ojan, 2014-03-13 23:25:16]

On 2014/03/13 22:08:08, eae wrote:
> On 2014/03/13 21:53:23, ojan wrote:
> > On 2014/03/13 21:38:00, eae wrote:
> > > On 2014/03/13 20:42:17, dglazkov wrote:
> > > > lgtm. Does this need to be behind flag for now?
> > > 
> > > It has no effect yet (other than exposing it through computed style). My
> plan
> > is
> > > to have the actual implementation behind a flag but not the plumbing as
the
> > > number of entry points would result in a lot of flag checks.
> > 
> > It also exposes it on the style property on Element. The problem with this
is
> > that it breaks feature detection. I swear we have a way to conditionalize
CSS
> > property names on a RuntimeEnabledFeature flag, but I can't seem to find it.
> > Eric, do you know?
> 
> It is already exposed that way, "typeof document.body.style.fontStretch"
returns
> string in chrome going back at least a year.

That's a bummer. I suppose it doesn't make sense to block you if this cat's
already out of the bag.

lgtm

[eae, 2014-03-14 17:05:47]

The CQ bit was checked by eae@chromium.org

[commit-bot: I haz the power, 2014-03-14 17:05:56]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/eae@chromium.org/199423003/20001

[commit-bot: I haz the power, 2014-03-14 17:57:56]

Change committed as 169264