CSS:Selector: Align with 3.x, remove the outer `selector.js` wrapper

Bring some changes from `3.x-stable`:
* rename `rtrim` to `rtrimCSS` to distinguish from the previous `rtrim`
  regex used for `jQuery.trim`
* backport one `id` selector test that avoids the selector engine path

Other changes:
* remove the inner function wrapper from `selector.js` by renaming
  the imported `document.js` value
* use `jQuery.error` in `selectorError`
* make Selector tests pass in all-modules runs by fixing a sinon mistake
  in Core tests - Core tests had a spy set up for `jQuery.error` that wasn't
  cleaned up, influencing Selector tests when all were run together

Closes gh-5295

6 files changed, 27 insertions, 20 deletions

diff --git a/src/css/curCSS.js b/src/css/curCSS.js
index 16104d893..b0f0a7555 100644
--- a/src/css/curCSS.js
+++ b/src/css/curCSS.js
@@ -2,7 +2,7 @@ import { jQuery } from "../core.js";
 import { isAttached } from "../core/isAttached.js";
 import { getStyles } from "./var/getStyles.js";
 import { rcustomProp } from "./var/rcustomProp.js";
-import { rtrim } from "../var/rtrim.js";
+import { rtrimCSS } from "../var/rtrimCSS.js";
 
 export function curCSS( elem, name, computed ) {
 	var ret,
@@ -41,12 +41,12 @@ export function curCSS( elem, name, computed ) {
 			// allowing us to differentiate them without a performance penalty
 			// and returning `undefined` aligns with older jQuery.
 			//
-			// rtrim treats U+000D CARRIAGE RETURN and U+000C FORM FEED
+			// rtrimCSS treats U+000D CARRIAGE RETURN and U+000C FORM FEED
 			// as whitespace while CSS does not, but this is not a problem
 			// because CSS preprocessing replaces them with U+000A LINE FEED
 			// (which *is* CSS whitespace)
 			// https://www.w3.org/TR/css-syntax-3/#input-preprocessing
-			ret = ret.replace( rtrim, "$1" ) || undefined;
+			ret = ret.replace( rtrimCSS, "$1" ) || undefined;
 		}
 
 		if ( ret === "" && !isAttached( elem ) ) {
diff --git a/src/selector.js b/src/selector.js
index 92bfcfed3..d71e65ad4 100644
--- a/src/selector.js
+++ b/src/selector.js
@@ -1,12 +1,12 @@
 import { jQuery } from "./core.js";
 import { nodeName } from "./core/nodeName.js";
-import { document } from "./var/document.js";
+import { document as preferredDoc } from "./var/document.js";
 import { indexOf } from "./var/indexOf.js";
 import { pop } from "./var/pop.js";
 import { push } from "./var/push.js";
 import { whitespace } from "./var/whitespace.js";
 import { rbuggyQSA } from "./selector/rbuggyQSA.js";
-import { rtrim } from "./var/rtrim.js";
+import { rtrimCSS } from "./var/rtrimCSS.js";
 import { isIE } from "./var/isIE.js";
 import { identifier } from "./selector/var/identifier.js";
 import { booleans } from "./selector/var/booleans.js";
@@ -27,10 +27,6 @@ import { toSelector } from "./selector/toSelector.js";
 import "./selector/escapeSelector.js";
 import "./selector/uniqueSort.js";
 
-var preferredDoc = document;
-
-( function() {
-
 var i,
 	outermostContext,
 
@@ -167,7 +163,11 @@ function find( selector, context, results, seed ) {
 
 					// Outside of IE, if we're not changing the context we can
 					// use :scope instead of an ID.
-					if ( newContext !== context || isIE ) {
+					// Support: IE 11+
+					// IE sometimes throws a "Permission denied" error when strict-comparing
+					// two documents; shallow comparisons work.
+					// eslint-disable-next-line eqeqeq
+					if ( newContext != context || isIE ) {
 
 						// Capture the context ID, setting it first if necessary
 						if ( ( nid = context.getAttribute( "id" ) ) ) {
@@ -204,7 +204,7 @@ function find( selector, context, results, seed ) {
 	}
 
 	// All others
-	return select( selector.replace( rtrim, "$1" ), context, results, seed );
+	return select( selector.replace( rtrimCSS, "$1" ), context, results, seed );
 }
 
 /**
@@ -632,7 +632,7 @@ jQuery.expr = {
 			// spaces as combinators
 			var input = [],
 				results = [],
-				matcher = compile( selector.replace( rtrim, "$1" ) );
+				matcher = compile( selector.replace( rtrimCSS, "$1" ) );
 
 			return matcher[ jQuery.expando ] ?
 				markFunction( function( seed, matches, _context, xml ) {
@@ -1070,7 +1070,12 @@ function matcherFromTokens( tokens ) {
 			return indexOf.call( checkContext, elem ) > -1;
 		}, implicitRelative, true ),
 		matchers = [ function( elem, context, xml ) {
-			var ret = ( !leadingRelative && ( xml || context !== outermostContext ) ) || (
+
+			// Support: IE 11+
+			// IE sometimes throws a "Permission denied" error when strict-comparing
+			// two documents; shallow comparisons work.
+			// eslint-disable-next-line eqeqeq
+			var ret = ( !leadingRelative && ( xml || context != outermostContext ) ) || (
 				( checkContext = context ).nodeType ?
 					matchContext( elem, context, xml ) :
 					matchAnyContext( elem, context, xml ) );
@@ -1104,7 +1109,7 @@ function matcherFromTokens( tokens ) {
 						// If the preceding token was a descendant combinator, insert an implicit any-element `*`
 						tokens.slice( 0, i - 1 )
 							.concat( { value: tokens[ i - 2 ].type === " " ? "*" : "" } )
-					).replace( rtrim, "$1" ),
+					).replace( rtrimCSS, "$1" ),
 					matcher,
 					i < j && matcherFromTokens( tokens.slice( i, j ) ),
 					j < len && matcherFromTokens( ( tokens = tokens.slice( j ) ) ),
@@ -1369,6 +1374,4 @@ find.select = select;
 find.setDocument = setDocument;
 find.tokenize = tokenize;
 
-} )();
-
 export { jQuery, jQuery as $ };
diff --git a/src/selector/rbuggyQSA.js b/src/selector/rbuggyQSA.js
index 7e4632c7f..b056ffe75 100644
--- a/src/selector/rbuggyQSA.js
+++ b/src/selector/rbuggyQSA.js
@@ -2,6 +2,8 @@ import { isIE } from "../var/isIE.js";
 import { whitespace } from "../var/whitespace.js";
 import { support } from "./support.js";
 
+// Build QSA regex.
+// Regex strategy adopted from Diego Perini.
 export var rbuggyQSA = [];
 
 if ( isIE ) {
diff --git a/src/selector/selectorError.js b/src/selector/selectorError.js
index 69770ec6a..da2b239f9 100644
--- a/src/selector/selectorError.js
+++ b/src/selector/selectorError.js
@@ -1,3 +1,5 @@
+import { jQuery } from "../core.js";
+
 export function selectorError( msg ) {
-	throw new Error( "Syntax error, unrecognized expression: " + msg );
+	jQuery.error( "Syntax error, unrecognized expression: " + msg );
 }
diff --git a/src/selector/tokenize.js b/src/selector/tokenize.js
index 3c1e06c46..fb25cb207 100644
--- a/src/selector/tokenize.js
+++ b/src/selector/tokenize.js
@@ -1,7 +1,7 @@
 import { jQuery } from "../core.js";
 import { rcomma } from "./var/rcomma.js";
 import { rleadingCombinator } from "./var/rleadingCombinator.js";
-import { rtrim } from "../var/rtrim.js";
+import { rtrimCSS } from "../var/rtrimCSS.js";
 import { createCache } from "./createCache.js";
 import { selectorError } from "./selectorError.js";
 import { filterMatchExpr } from "./filterMatchExpr.js";
@@ -42,7 +42,7 @@ export function tokenize( selector, parseOnly ) {
 				value: matched,
 
 				// Cast descendant combinators to space
-				type: match[ 0 ].replace( rtrim, " " )
+				type: match[ 0 ].replace( rtrimCSS, " " )
 			} );
 			soFar = soFar.slice( matched.length );
 		}
diff --git a/src/var/rtrim.js b/src/var/rtrimCSS.js
index aa20c961c..f35b8a1e9 100644
--- a/src/var/rtrim.js
+++ b/src/var/rtrimCSS.js
@@ -1,6 +1,6 @@
 import { whitespace } from "./whitespace.js";
 
-export var rtrim = new RegExp(
+export var rtrimCSS = new RegExp(
 	"^" + whitespace + "+|((?:^|[^\\\\])(?:\\\\.)*)" + whitespace + "+$",
 	"g"
 );