jquery / sizzle

jquery-release only updates the version in the tag so it stays stale on master.
Instead, just remove the version from there.

Closes gh-469

Running `grunt` will now just build Sizzle, do a size comparison & run ESLint,
similarly to what we do in jQuery. `grunt test` is used to run unit tests and
it requires running `grunt` or `grunt build` before to generate the built
Sizzle version.

Fixes gh-239
Closes gh-467

qSA in IE 11/Edge often (but not always) don't find elements with an empty
name attribute selector (`[name=""]`). Detect that & fall back to Sizzle
traversal.

Interestingly, IE 10 & older don't seem to have the issue.

Closes gh-461
Fixes jquery/jquery#4435

PR gh-456 introduced a test catching not throwing on badly-escaped identifiers
by Firefox 3.6-5. Unfortunately, it was placed just before a test Opera 10-11
fails, making Opera fail quicker and not adding a post-comma invalid selector
to rbuggyQSA.

This commit fixes the regression & introduces a unit test ensuring the throwing.
Unfortunately, the issue is fixed in Opera 11.6 which is the lowest one Sizzle
officially supports but I verified the fix manually against Opera 10.6, 11.1
& 11.5.

Closes gh-463
Ref gh-456

There was a test for Shadow DOM nodes working as root but it was using Shadow
DOM v0 that only Chromium implements and which it plans to remove in the future.
The test was reworked to rely on Shadow DOM v1.

jQuery master already uses the new API in its tests.

Closes gh-464

Closes gh-462

An optimization added in #431 skips the temporary IDs for selectors
not using child or descendant combinators. For sibling combinators, though, this
pushes a selector with a leading combinator to qSA directly which crashes and
falls back to a slower Sizzle route.

This commit makes selectors with leading combinators not skip the selector
rewriting. Note that after jquery/jquery#4454 & #453, all modern
browsers other than Edge leverage the :scope pseudo-class, avoiding temporary
id attributes.

Closes gh-460
Ref gh-431

The `:scope` pseudo-class[1] has surprisingly good browser support: Chrome,
Firefox & Safari have supported if for a long time; only IE & Edge lack support.
This commit leverages this pseudo-class to get rid of the ID hack in most cases.
Adding a temporary ID may cause layout thrashing which was reported a few times
in [the past.

We can't completely eliminate the ID hack in modern browses as sibling selectors
require us to change context to the parent and then `:scope` stops applying to
what we'd like. But it'd still improve performance in the vast majority of
cases.

[1] https://developer.mozilla.org/en-US/docs/Web/CSS/:scope

Fixes jquery/jquery#4453
Closes gh-453
Ref jquery/jquery#4454
Ref jquery/jquery#4332
Ref gh-405

IE/Edge sometimes crash when comparing documents between frames using the strict
equality operator (`===` & `!==`). Funnily enough, shallow comparisons
(`==` & `!=`) work without crashing.

Fixes jquery/jquery#4441
Closes gh-459
Ref jquery/jquery#4471

The Karma version currently used by Sizzle often re-runs tests in all browsers
from the current browser set if one of them fails. To improve reliability, split
iOS into two browser sets similarly to how desktop browsers & Android are split.

Closes gh-457

…rovements

Sizzle hasn't been able to finish all its unit tests successfully for a long time. This commit attempts to make it work again (at least most of the time).

Summary of the changes:
1. A new "karma-tests" task is created; it runs tests in various browser sets
but does it sequentially in separate processes to avoid Karma bugs that cause
browsers from previous sets to somehow still be waited on during subsequent
runs, failing the build.
2. Upgrade tested browsers.
3. Run iOS tests at the end (as it fails more often than other browsers).
4. Use real iOS 10.3 device in Karma.

We can't upgrade Karma as the latest version (`4.2.0`) hangs in IE 7 (IE 8 seems to work fine there).

Closes gh-455

According to:
https://www.w3.org/TR/css-syntax-3/#ident-token-diagram
the escape doesn't need to be followed by a whitespace only if it's not a hex
digit or a newline. However, old Firefox (3.6 - 5 only) doesn't throw if an
escaped newline is not followed by a space. Fallback to Sizzle in such cases.

Fixes gh-454
Closes gh-456

Closes gh-451

Ref jquery/jquery#4424
Closes gh-450

Newest eslint-config-jquery requires prefixing unused function parameters with
and underscore; that has been done. The build Grunt task was also fixed to lint
the built Sizzle version only after it's built.

Ref gh-442

Fixes gh-438
Closes gh-442

Closes gh-439

Closes gh-446

Also, test raw whitespace handling of :contains matching

Fixes gh-335
Closes gh-437

Fixes gh-378
Closes gh-436

Firefox, Chrome, Edge & Opera have been updated.

iOS 12.0 stopped working but there's a working 12.1 available so I switched
to that one.

Ref gh-239
Ref gh-308
Closes gh-433

Ref 71fe25c

Fixes gh-430
Closes gh-431

Closes #434

Closes #419

Closes #432