Added parseShorthand method from the parser to CSSPropertyAPI.h.

Added parseShorthand method from the parser to CSSPropertyAPI.h.

A part of Project Ribbon, separating the parsing logic for CSS
properties from the parser into an API. This patch adds a new method to
CSSPropertyAPI.h, parseShorthand, and provides a default NOTREACHED()
implementation for this method.

When a property implements parseShorthand in it's API implementation in
CSSPropertyAPI(.*).cpp, a function pointer to the parse function from
the API for this property is stored in a CSSPropertyDescriptor, and is
called from CSSPropertyParser. If parseShorthand is not yet implemented
for a property, the existing switch statement handles this property.

This patch:
- Modifies CSSPropertyDescriptor.cpp.tmpl so that the parseShorthand
  method is added to the generated descriptors.
- Adds parseShorthand to CSSPropertyAPI.h.
- Adds a function pointer for parseShorthand to the struct in
  CSSPropertyDescriptor.h. Also removes temporaryCanReadValue from this
  struct.
- Modifies parseShorthand in CSSPropertyDescriptor.h so that the API
  is called if an implementation exists.

BUG=668012
Review-Url: https://codereview.chromium.org/2653733005
Cr-Commit-Position: refs/heads/master@{#448174}
Committed: https://chromium.googlesource.com/chromium/src/+/23da976a5a8354e876e523c942aa0350f404bd74

[aazzam, 2017-01-24 00:21:55]

Description was changed from

==========
Added parseShorthand method from the parser to CSSPropertyAPI.h.

A part of Project Ribbon, separating the parsing logic for CSS
properties from the parser into an API. This patch adds a new method to
CSSPropertyAPI.h, parseShorthand, and provides a default NOTREACHED()
implementation for this method.

When a property implements parseShorthand in it's API implementation in
CSSPropertyAPI(.*).cpp, a function pointer to the parse function from
the API for this property is stored in a CSSPropertyDescriptor, and is
called from CSSPropertyParser. If parseShorthand is not yet implemented
for a property, the existing switch statement handles this property.

BUG=668012
==========

to

==========
Added parseShorthand method from the parser to CSSPropertyAPI.h.

A part of Project Ribbon, separating the parsing logic for CSS
properties from the parser into an API. This patch adds a new method to
CSSPropertyAPI.h, parseShorthand, and provides a default NOTREACHED()
implementation for this method.

When a property implements parseShorthand in it's API implementation in
CSSPropertyAPI(.*).cpp, a function pointer to the parse function from
the API for this property is stored in a CSSPropertyDescriptor, and is
called from CSSPropertyParser. If parseShorthand is not yet implemented
for a property, the existing switch statement handles this property.

This patch:
- Modifies CSSPropertyDescriptor.cpp.tmpl so that the parseShorthand
  method is added to the generated descriptors.
- Adds parseShorthand to CSSPropertyAPI.h.
- Adds a function pointer for parseShorthand to the struct in
  CSSPropertyDescriptor.h. Also removes temporaryCanReadValue from this
  struct.
- Modifies parseShorthand in CSSPropertyDescriptor.h so that the API
  is called if an implementation exists.

BUG=668012
==========

[aazzam, 2017-01-24 05:45:42]

aazzam@google.com changed reviewers:
+ meade@chromium.org

[aazzam, 2017-01-24 05:45:43]

hey eddy! ptal :) especially would like feedback on the
FUNCTION_IMPLEMENTED_FOR_PROPERTY macro (it's name, paramaters, location..) and
on my CL description

[meade_UTC10, 2017-01-25 04:23:59]

The CQ bit was checked by meade@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-01-25 04:24:19]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-01-25 04:26:12]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-01-25 04:26:12]

Dry run: Try jobs failed on following builders:
  chromium_presubmit on master.tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/chromium_presub...)
  ios-device on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios-device/builds...)
  ios-device-xcode-clang on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios-device-xcode-...)
  ios-simulator-xcode-clang on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios-simulator-xco...)

[meade_UTC10, 2017-01-25 04:28:18]

lgtm

The CL description and macro names seem fine to me, the only thing I didn't
really understand were the existing comments...

https://codereview.chromium.org/2653733005/diff/60001/third_party/WebKit/Sour...
File
third_party/WebKit/Source/build/scripts/templates/CSSPropertyDescriptor.cpp.tmpl
(right):

https://codereview.chromium.org/2653733005/diff/60001/third_party/WebKit/Sour...
third_party/WebKit/Source/build/scripts/templates/CSSPropertyDescriptor.cpp.tmpl:19:
// struct initaliser.
I'm not sure I understand what this does, it's creating a 2D array of function
pointers or null?

https://codereview.chromium.org/2653733005/diff/60001/third_party/WebKit/Sour...
third_party/WebKit/Source/build/scripts/templates/CSSPropertyDescriptor.cpp.tmpl:24:
{ {{api_class.classname}}::parseSingleValue,
{{api_class.classname}}::parseShorthand },
And in this case it's defining the default implementation and the subclass
implementation for this particular value..?

[aazzam, 2017-01-25 04:35:19]

eddy ptal at comment reply :)

https://codereview.chromium.org/2653733005/diff/60001/third_party/WebKit/Sour...
File
third_party/WebKit/Source/build/scripts/templates/CSSPropertyDescriptor.cpp.tmpl
(right):

https://codereview.chromium.org/2653733005/diff/60001/third_party/WebKit/Sour...
third_party/WebKit/Source/build/scripts/templates/CSSPropertyDescriptor.cpp.tmpl:24:
{ {{api_class.classname}}::parseSingleValue,
{{api_class.classname}}::parseShorthand },
On 2017/01/25 at 04:28:18, Eddy wrote:
> And in this case it's defining the default implementation and the subclass
implementation for this particular value..?

the array cssPropertyDescriptors stores an invalid descriptor as the first
element, and a descriptor for each property with an implementation as every
other element. So the invalid descriptor is just nullptr for all the function
pointers. For every other descriptor, it will have a function pointer for
parseSingleValue, parseShorthand, etc. for that property

This CL just changes these struct initialiser lists so that they don't have the
bool value (I removed temporaryCanReadValue from the CSSPropertyDescriptor
struct) and added a pointer for parseShorthand, since this function was added to
the descriptor.

does that clarify your questions? :)

[meade_UTC10, 2017-01-25 05:26:27]

https://codereview.chromium.org/2653733005/diff/60001/third_party/WebKit/Sour...
File
third_party/WebKit/Source/build/scripts/templates/CSSPropertyDescriptor.cpp.tmpl
(right):

https://codereview.chromium.org/2653733005/diff/60001/third_party/WebKit/Sour...
third_party/WebKit/Source/build/scripts/templates/CSSPropertyDescriptor.cpp.tmpl:24:
{ {{api_class.classname}}::parseSingleValue,
{{api_class.classname}}::parseShorthand },
On 2017/01/25 04:35:19, aazzam wrote:
> On 2017/01/25 at 04:28:18, Eddy wrote:
> > And in this case it's defining the default implementation and the subclass
> implementation for this particular value..?
> 
> the array cssPropertyDescriptors stores an invalid descriptor as the first
> element, and a descriptor for each property with an implementation as every
> other element. So the invalid descriptor is just nullptr for all the function
> pointers. For every other descriptor, it will have a function pointer for
> parseSingleValue, parseShorthand, etc. for that property
> 
> This CL just changes these struct initialiser lists so that they don't have
the
> bool value (I removed temporaryCanReadValue from the CSSPropertyDescriptor
> struct) and added a pointer for parseShorthand, since this function was added
to
> the descriptor.
> 
> does that clarify your questions? :)

Maybe? :) I think it's worth changing the comments and/or code to make this
clearer. A couple of comments on this...

1- It's possible to have too many comments (!) - I think there were too many
words about what to do if you add a function to the CSSPropertyAPI that I lost
the meaning of the code.

2- I'd discourage having the first (or last) entry in an array being a special
value (sounds like a trap for people unfamilar with the code who might try
iterating everything obliviously)... You could split it out into two variables:

// An invalid CSSPropertyDescriptor containing null placeholders for each 
// method that could possibly be supported by a descriptor. It should have the 
// same length as each entry in cssPropertyDescriptors.
static CSSPropertyDescriptor invalidDescriptor[] = {nullptr, nullptr};
static CSSPropertyDescriptor cssPropertyDescriptors[] = {
  { {{api_class.classname}}::parseSingleValue,
      {{api_class.classname}}::parseShorthand },
};


Also: feel free to address these comments in a followup CL.

[aazzam, 2017-01-25 06:11:10]

On 2017/01/25 at 05:26:27, meade wrote:
>
https://codereview.chromium.org/2653733005/diff/60001/third_party/WebKit/Sour...
> File
third_party/WebKit/Source/build/scripts/templates/CSSPropertyDescriptor.cpp.tmpl
(right):
> 
>
https://codereview.chromium.org/2653733005/diff/60001/third_party/WebKit/Sour...
>
third_party/WebKit/Source/build/scripts/templates/CSSPropertyDescriptor.cpp.tmpl:24:
{ {{api_class.classname}}::parseSingleValue,
{{api_class.classname}}::parseShorthand },
> On 2017/01/25 04:35:19, aazzam wrote:
> > On 2017/01/25 at 04:28:18, Eddy wrote:
> > > And in this case it's defining the default implementation and the subclass
> > implementation for this particular value..?
> > 
> > the array cssPropertyDescriptors stores an invalid descriptor as the first
> > element, and a descriptor for each property with an implementation as every
> > other element. So the invalid descriptor is just nullptr for all the
function
> > pointers. For every other descriptor, it will have a function pointer for
> > parseSingleValue, parseShorthand, etc. for that property
> > 
> > This CL just changes these struct initialiser lists so that they don't have
the
> > bool value (I removed temporaryCanReadValue from the CSSPropertyDescriptor
> > struct) and added a pointer for parseShorthand, since this function was
added to
> > the descriptor.
> > 
> > does that clarify your questions? :)
> 
> Maybe? :) I think it's worth changing the comments and/or code to make this
clearer. A couple of comments on this...
> 
> 1- It's possible to have too many comments (!) - I think there were too many
words about what to do if you add a function to the CSSPropertyAPI that I lost
the meaning of the code.
> 
> 2- I'd discourage having the first (or last) entry in an array being a special
value (sounds like a trap for people unfamilar with the code who might try
iterating everything obliviously)... You could split it out into two variables:
> 
> // An invalid CSSPropertyDescriptor containing null placeholders for each 
> // method that could possibly be supported by a descriptor. It should have the

> // same length as each entry in cssPropertyDescriptors.
> static CSSPropertyDescriptor invalidDescriptor[] = {nullptr, nullptr};
> static CSSPropertyDescriptor cssPropertyDescriptors[] = {
>   { {{api_class.classname}}::parseSingleValue,
>       {{api_class.classname}}::parseShorthand },
> };
> 
> 
> Also: feel free to address these comments in a followup CL.

okay yep! thanks for that eddy, I agree and I think splitting it up would be
better. I'll do this in a follow up patch since this design wasn't made in this
CL, and isn't very relevant either :)

[aazzam, 2017-01-26 22:36:29]

aazzam@google.com changed reviewers:
+ sashab@chromium.org

[aazzam, 2017-01-26 22:36:29]

PTAL sasha! :)

[aazzam, 2017-01-27 05:28:31]

The CQ bit was checked by aazzam@google.com to run a CQ dry run

[commit-bot: I haz the power, 2017-01-27 05:28:50]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-01-27 05:30:36]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-01-27 05:30:39]

Dry run: Try jobs failed on following builders:
  ios-device on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios-device/builds...)
  ios-device-xcode-clang on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios-device-xcode-...)
  ios-simulator on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios-simulator/bui...)
  ios-simulator-xcode-clang on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios-simulator-xco...)

[sashab, 2017-01-27 22:06:00]

This looks great, and I'm happy to go ahead with this approach if you'd like
(I'll review it properly). But is this out of date now with the new design? Or
is this a stepping-stone towards that design? LMK :)

[aazzam, 2017-01-31 03:10:33]

aazzam@google.com changed reviewers:
+ nainar@chromium.org

[aazzam, 2017-01-31 03:10:34]

please take a look naina! :)

[nainar, 2017-01-31 03:24:11]

lgtm

[aazzam, 2017-01-31 03:46:39]

ptal sasha! :)

[sashab, 2017-01-31 22:58:14]

Hmm, some design choices here to think about :) Overall looking on the right
track though

https://codereview.chromium.org/2653733005/diff/140001/third_party/WebKit/Sou...
File third_party/WebKit/Source/build/scripts/make_css_property_apis.py (right):

https://codereview.chromium.org/2653733005/diff/140001/third_party/WebKit/Sou...
third_party/WebKit/Source/build/scripts/make_css_property_apis.py:29:
valid_methods = ["parseSingleValue", "parseShorthand"]
Need to rebase this :)

https://codereview.chromium.org/2653733005/diff/140001/third_party/WebKit/Sou...
File third_party/WebKit/Source/core/css/parser/CSSPropertyParser.cpp (right):

https://codereview.chromium.org/2653733005/diff/140001/third_party/WebKit/Sou...
third_party/WebKit/Source/core/css/parser/CSSPropertyParser.cpp:2083: if
(FUNCTION_IMPLEMENTED_FOR_PROPERTY(parseSingleValue, cssPropertyDesc) &&
Sorry to do this, but this should really be in a separate patch :( I think it's
OK this time, but in future please split out features into individual pieces so
we can review them independently:)

https://codereview.chromium.org/2653733005/diff/140001/third_party/WebKit/Sou...
third_party/WebKit/Source/core/css/parser/CSSPropertyParser.cpp:3581: // Gets
the parsing function for our current property from the property API.
function -> method (keep naming consistent)

https://codereview.chromium.org/2653733005/diff/140001/third_party/WebKit/Sou...
third_party/WebKit/Source/core/css/parser/CSSPropertyParser.cpp:3582: // If it
has been implemented, we call this function, otherwise we manually
function -> method

https://codereview.chromium.org/2653733005/diff/140001/third_party/WebKit/Sou...
File third_party/WebKit/Source/core/css/properties/CSSPropertyAPI.h (right):

https://codereview.chromium.org/2653733005/diff/140001/third_party/WebKit/Sou...
third_party/WebKit/Source/core/css/properties/CSSPropertyAPI.h:51: NOTREACHED();
Add similar comment above this :)

https://codereview.chromium.org/2653733005/diff/140001/third_party/WebKit/Sou...
File third_party/WebKit/Source/core/css/properties/CSSPropertyDescriptor.h
(right):

https://codereview.chromium.org/2653733005/diff/140001/third_party/WebKit/Sou...
third_party/WebKit/Source/core/css/properties/CSSPropertyDescriptor.h:13:
#define FUNCTION_IMPLEMENTED_FOR_PROPERTY(function, descriptor) \
This can be rebased now? :)

If not make it METHOD_IMPLENTED_FOR_PROPERTY
or even API_METHOD_IMPLEMENTED_FOR_PROPERTY
or IS_API_METHOD_...

Ask darren for his opinion ;)

[aazzam, 2017-02-01 00:30:05]

ptal sasha :)
changed a bit now that there's a rebase with
https://codereview.chromium.org/2670433002

https://codereview.chromium.org/2653733005/diff/140001/third_party/WebKit/Sou...
File third_party/WebKit/Source/build/scripts/make_css_property_apis.py (right):

https://codereview.chromium.org/2653733005/diff/140001/third_party/WebKit/Sou...
third_party/WebKit/Source/build/scripts/make_css_property_apis.py:29:
valid_methods = ["parseSingleValue", "parseShorthand"]
On 2017/01/31 at 22:58:14, sashab wrote:
> Need to rebase this :)

rebased :)

https://codereview.chromium.org/2653733005/diff/140001/third_party/WebKit/Sou...
File third_party/WebKit/Source/core/css/parser/CSSPropertyParser.cpp (right):

https://codereview.chromium.org/2653733005/diff/140001/third_party/WebKit/Sou...
third_party/WebKit/Source/core/css/parser/CSSPropertyParser.cpp:3582: // If it
has been implemented, we call this function, otherwise we manually
On 2017/01/31 at 22:58:14, sashab wrote:
> function -> method

fixed, also fixed in comment near parseSingleValue :)

https://codereview.chromium.org/2653733005/diff/140001/third_party/WebKit/Sou...
File third_party/WebKit/Source/core/css/properties/CSSPropertyAPI.h (right):

https://codereview.chromium.org/2653733005/diff/140001/third_party/WebKit/Sou...
third_party/WebKit/Source/core/css/properties/CSSPropertyAPI.h:51: NOTREACHED();
On 2017/01/31 at 22:58:14, sashab wrote:
> Add similar comment above this :)

added :)

https://codereview.chromium.org/2653733005/diff/140001/third_party/WebKit/Sou...
File third_party/WebKit/Source/core/css/properties/CSSPropertyDescriptor.h
(right):

https://codereview.chromium.org/2653733005/diff/140001/third_party/WebKit/Sou...
third_party/WebKit/Source/core/css/properties/CSSPropertyDescriptor.h:13:
#define FUNCTION_IMPLEMENTED_FOR_PROPERTY(function, descriptor) \
On 2017/01/31 at 22:58:14, sashab wrote:
> This can be rebased now? :)
> 
> If not make it METHOD_IMPLENTED_FOR_PROPERTY
> or even API_METHOD_IMPLEMENTED_FOR_PROPERTY
> or IS_API_METHOD_...
> 
> Ask darren for his opinion ;)

this is gone with the new patch of changing the descriptor, since now the check
for implementation is just
if (cssPropertyDesc.parseSingleValue) // i.e. check if not nullptr

[sashab, 2017-02-01 18:21:46]

Storing nullptr makes this so much nicer!! We should store this patch as an
example of what a patch looks like to add a property to the API. And it's
looking nice and simple. :)

Just a few more questions :) But def on the right track

https://codereview.chromium.org/2653733005/diff/160001/third_party/WebKit/Sou...
File
third_party/WebKit/Source/build/scripts/templates/CSSPropertyDescriptor.cpp.tmpl
(left):

https://codereview.chromium.org/2653733005/diff/160001/third_party/WebKit/Sou...
third_party/WebKit/Source/build/scripts/templates/CSSPropertyDescriptor.cpp.tmpl:33:
},
Why did you remove this line? :)

https://codereview.chromium.org/2653733005/diff/160001/third_party/WebKit/Sou...
File third_party/WebKit/Source/core/css/parser/CSSPropertyParser.cpp (right):

https://codereview.chromium.org/2653733005/diff/160001/third_party/WebKit/Sou...
third_party/WebKit/Source/core/css/parser/CSSPropertyParser.cpp:45: #include
"core/css/properties/CSSPropertyAPI.h"
Why is this needed?

https://codereview.chromium.org/2653733005/diff/160001/third_party/WebKit/Sou...
third_party/WebKit/Source/core/css/parser/CSSPropertyParser.cpp:3625: // If
Fix weird commenting thing :)

[sashab, 2017-02-01 18:22:02]

Actually once you fix those LGTM :)

[aazzam, 2017-02-05 02:11:30]

The CQ bit was checked by aazzam@google.com

[aazzam, 2017-02-05 02:11:31]

The patchset sent to the CQ was uploaded after l-g-t-m from meade@chromium.org,
nainar@chromium.org, sashab@chromium.org
Link to the patchset: https://codereview.chromium.org/2653733005/#ps180001
(title: "Neatened up code")

[commit-bot: I haz the power, 2017-02-05 02:11:38]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-02-05 02:13:10]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-02-05 02:13:12]

Try jobs failed on following builders:
  ios-device on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios-device/builds...)
  ios-device-xcode-clang on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios-device-xcode-...)
  ios-simulator on master.tryserver.chromium.mac (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.mac/builders/ios-simulator/bui...)

[aazzam, 2017-02-05 02:49:41]

The CQ bit was checked by aazzam@google.com

[aazzam, 2017-02-05 02:49:42]

The patchset sent to the CQ was uploaded after l-g-t-m from meade@chromium.org,
nainar@chromium.org, sashab@chromium.org
Link to the patchset: https://codereview.chromium.org/2653733005/#ps200001
(title: "rebase")

[commit-bot: I haz the power, 2017-02-05 02:49:55]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-02-05 04:32:52]

CQ is committing da patch.

Bot data: {"patchset_id": 200001, "attempt_start_ts": 1486262981438050,
"parent_rev": "04055dd2786e27cde8d210b68e7a726fab6d0c42", "commit_rev":
"23da976a5a8354e876e523c942aa0350f404bd74"}

[commit-bot: I haz the power, 2017-02-05 04:33:24]

Description was changed from

==========
Added parseShorthand method from the parser to CSSPropertyAPI.h.

A part of Project Ribbon, separating the parsing logic for CSS
properties from the parser into an API. This patch adds a new method to
CSSPropertyAPI.h, parseShorthand, and provides a default NOTREACHED()
implementation for this method.

When a property implements parseShorthand in it's API implementation in
CSSPropertyAPI(.*).cpp, a function pointer to the parse function from
the API for this property is stored in a CSSPropertyDescriptor, and is
called from CSSPropertyParser. If parseShorthand is not yet implemented
for a property, the existing switch statement handles this property.

This patch:
- Modifies CSSPropertyDescriptor.cpp.tmpl so that the parseShorthand
  method is added to the generated descriptors.
- Adds parseShorthand to CSSPropertyAPI.h.
- Adds a function pointer for parseShorthand to the struct in
  CSSPropertyDescriptor.h. Also removes temporaryCanReadValue from this
  struct.
- Modifies parseShorthand in CSSPropertyDescriptor.h so that the API
  is called if an implementation exists.

BUG=668012
==========

to

==========
Added parseShorthand method from the parser to CSSPropertyAPI.h.

A part of Project Ribbon, separating the parsing logic for CSS
properties from the parser into an API. This patch adds a new method to
CSSPropertyAPI.h, parseShorthand, and provides a default NOTREACHED()
implementation for this method.

When a property implements parseShorthand in it's API implementation in
CSSPropertyAPI(.*).cpp, a function pointer to the parse function from
the API for this property is stored in a CSSPropertyDescriptor, and is
called from CSSPropertyParser. If parseShorthand is not yet implemented
for a property, the existing switch statement handles this property.

This patch:
- Modifies CSSPropertyDescriptor.cpp.tmpl so that the parseShorthand
  method is added to the generated descriptors.
- Adds parseShorthand to CSSPropertyAPI.h.
- Adds a function pointer for parseShorthand to the struct in
  CSSPropertyDescriptor.h. Also removes temporaryCanReadValue from this
  struct.
- Modifies parseShorthand in CSSPropertyDescriptor.h so that the API
  is called if an implementation exists.

BUG=668012

Review-Url: https://codereview.chromium.org/2653733005
Cr-Commit-Position: refs/heads/master@{#448174}
Committed:
https://chromium.googlesource.com/chromium/src/+/23da976a5a8354e876e523c942aa...
==========

[commit-bot: I haz the power, 2017-02-05 04:33:25]

Committed patchset #11 (id:200001) as
https://chromium.googlesource.com/chromium/src/+/23da976a5a8354e876e523c942aa...