Promote new CSS parser to experimental

Promote new CSS parser to experimental

This patch promotes the new CSS parser to experimental, rebaselining the
tests with changed behaviour. The new parser will now handle everything
except for when the inspector uses a CSSParserObserver, which I'll add
support for soon.

In tests I ran on a Nexus 7 (2013 model), the new parser performed on
average 18% faster than the existing parser (independent of stylesheet
size). The only case which which didn't show an improvement were those
with extremely large strings ("url(data:font/opentype;base64,..." for
example).

There are quite a few really small behaviour changes. The following
changes affected existing layout tests which have been updated in this
patch:

- <an+b> serialization now matches the spec instead of just copying the
input. http://dev.w3.org/csswg/css-syntax/#serializing-anb

- @supports requires whitespace after not/or/and and before or/and. This
matches the spec and Firefox. Usage of the invalid syntax is virtually
zero. http://dev.w3.org/csswg/css-conditional-3/#at-supports

- CSSSupportsRule now serializes the condition instead of just copying
the input.

- Escapes with value 0 get replaced by U+FFFD
http://dev.w3.org/csswg/css-syntax/#consume-escaped-code-point

- Namespaces in selectors are only allowed in front of element names.
http://dev.w3.org/csswg/selectors-4/#grammar

- \r\n is considered a single whitespace (a single whitespace after an
escaped character is ignored, so we won't leave an extra whitespace now).
http://dev.w3.org/csswg/css-syntax/#input-preprocessing

- Escapes are now allowed in dimension types (although it probably never
makes sense to write 16\70\78 instead of 16px...)

- Strings will now be terminated at a newline (a <bad-string-token> is
produced), instead of continuing to look ahead of an ending quote.
http://dev.w3.org/csswg/css-syntax/#consume-string-token

I also noticed a few more behaviour changes which our layout tests don't
cover yet. Most of these are covered by unit tests, but I'll add layout
tests for some of these shortly:

- Null characters are now replaced by U+FFFD during tokenization.
http://dev.w3.org/csswg/css-syntax/#input-preprocessing

- We now reject scientific notation of the form "16e-px"
- We now reject percentages with extra %s (left: 10%%%)

- We now allow :nth-* case insensitively
- We now allow idents to start with --

- We now parse <an+b> and <quirky-color> in terms of CSS tokens
http://dev.w3.org/csswg/css-syntax/#the-anb-type
https://quirks.spec.whatwg.org/#the-hashless-hex-color-quirk

BUG=330389
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=192641

[Timothy Loh, 2015-03-20 05:51:16]

timloh@chromium.org changed reviewers:
+ alancutter@chromium.org, dstockwell@chromium.org, pdr@chromium.org

[Timothy Loh, 2015-03-20 05:58:50]

This patch depends on https://codereview.chromium.org/1018213004/ getting
reviewed and landed first. Aside from that, everything should work now in the
new parser (except CSSParserObserver codepaths as mentioned in the description).
I probably also need to rewrite parsing-css-allowed-string-characters.html so it
can go through the CQ :\

I'll write up a PSA to send to blink-dev next week with other sorts of details,
after which I'd like to ship this to stable. Assuming I don't get overloaded by
bug reports, we'll remove the Bison parser after the M43 branch point.

[Timothy Loh, 2015-03-20 05:59:14]

Patchset #2 (id:20001) has been deleted

[alancutter (OOO until 2018), 2015-03-26 05:38:20]

lgtm

[Timothy Loh, 2015-03-26 07:05:02]

pdr: PTAL for Source/platform/. I'll probably also send out a patch to move this
to stable super soon, but moving to experimental first will make it easier to
revert the flip to stable.

[Timothy Loh, 2015-03-26 07:07:23]

On 2015/03/26 07:05:02, Timothy Loh wrote:
> pdr: PTAL for Source/platform/. I'll probably also send out a patch to move
this
> to stable super soon, but moving to experimental first will make it easier to
> revert the flip to stable.

Not that I expect to have to revert it :)

[pdr., 2015-03-26 18:02:32]

On 2015/03/26 at 07:07:23, timloh wrote:
> On 2015/03/26 07:05:02, Timothy Loh wrote:
> > pdr: PTAL for Source/platform/. I'll probably also send out a patch to move
this
> > to stable super soon, but moving to experimental first will make it easier
to
> > revert the flip to stable.
> 
> Not that I expect to have to revert it :)

LGTM

[Timothy Loh, 2015-03-26 23:45:23]

The CQ bit was checked by timloh@chromium.org

[commit-bot: I haz the power, 2015-03-26 23:45:48]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1015303002/60001

[commit-bot: I haz the power, 2015-03-27 00:33:04]

Committed patchset #3 (id:60001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=192641