Core: Migrate from AMD to ES modules 🎉

Migrate all source AMD modules to ECMAScript modules. The final bundle
is compiled by a custom build process that uses Rollup under the hood.

Test files themselves are still loaded via RequireJS as that has to work in
IE 11.

Tests can now be run in "Load as modules" mode which replaces the previous
"Load with AMD" option. That option of running tests doesn't work in IE
and Edge as it requires support for dynamic imports.

Some of the changes required by the migration:
* check `typeof` of `noGlobal` instead of using the variable directly
  as it's not available when modules are used
* change the nonce module to be an object as ECMASscript module exports
  are immutable
* remove some unused exports
* import `./core/parseHTML.js` directly in `jquery.js` so that it's not
  being cut out when the `ajax` module is excluded in a custom compilation

Closes gh-4541

5 files changed, 11 insertions, 41 deletions

diff --git a/src/selector/contains.js b/src/selector/contains.js
index 0d6273c28..a62b97ab5 100644
--- a/src/selector/contains.js
+++ b/src/selector/contains.js
@@ -1,8 +1,4 @@
-define( [
-	"../core"
-], function( jQuery ) {
-
-"use strict";
+import jQuery from "../core.js";
 
 // Note: an element does not contain itself
 jQuery.contains = function( a, b ) {
@@ -18,5 +14,3 @@ jQuery.contains = function( a, b ) {
 			a.compareDocumentPosition && a.compareDocumentPosition( bup ) & 16
 	) );
 };
-
-} );
diff --git a/src/selector/escapeSelector.js b/src/selector/escapeSelector.js
index 1d89c2f00..bc61355fa 100644
--- a/src/selector/escapeSelector.js
+++ b/src/selector/escapeSelector.js
@@ -1,8 +1,4 @@
-define( [
-	"../core"
-], function( jQuery ) {
-
-"use strict";
+import jQuery from "../core.js";
 
 // CSS string/identifier serialization
 // https://drafts.csswg.org/cssom/#common-serializing-idioms
@@ -27,5 +23,3 @@ function fcssescape( ch, asCodePoint ) {
 jQuery.escapeSelector = function( sel ) {
 	return ( sel + "" ).replace( rcssescape, fcssescape );
 };
-
-} );
diff --git a/src/selector/rbuggyQSA.js b/src/selector/rbuggyQSA.js
index eee151afb..f638fc429 100644
--- a/src/selector/rbuggyQSA.js
+++ b/src/selector/rbuggyQSA.js
@@ -1,9 +1,5 @@
-define( [
-	"../var/document",
-	"../var/isIE"
-], function( document, isIE ) {
-
-"use strict";
+import document from "../var/document.js";
+import isIE from "../var/isIE.js";
 
 var rbuggyQSA = [],
 	testEl = document.createElement( "div" );
@@ -25,6 +21,4 @@ if ( isIE ) {
 
 rbuggyQSA = rbuggyQSA.length && new RegExp( rbuggyQSA.join( "|" ) );
 
-return rbuggyQSA;
-
-} );
+export default rbuggyQSA;
diff --git a/src/selector/support.js b/src/selector/support.js
index 86cd2d9ae..cc584bf66 100644
--- a/src/selector/support.js
+++ b/src/selector/support.js
@@ -1,9 +1,5 @@
-define( [
-	"../var/document",
-	"../var/support"
-], function( document, support ) {
-
-"use strict";
+import document from "../var/document.js";
+import support from "../var/support.js";
 
 // Support: IE 9 - 11+, Edge 12 - 18+
 // IE/Edge don't support the :scope pseudo-class.
@@ -12,6 +8,4 @@ try {
 	support.scope = true;
 } catch ( e ) {}
 
-return support;
-
-} );
+export default support;
diff --git a/src/selector/uniqueSort.js b/src/selector/uniqueSort.js
index ec97de849..d0bf69198 100644
--- a/src/selector/uniqueSort.js
+++ b/src/selector/uniqueSort.js
@@ -1,10 +1,6 @@
-define( [
-	"../core",
-	"../var/document",
-	"../var/sort"
-], function( jQuery, document, sort ) {
-
-"use strict";
+import jQuery from "../core.js";
+import document from "../var/document.js";
+import sort from "../var/sort.js";
 
 var hasDuplicate;
 
@@ -90,5 +86,3 @@ jQuery.uniqueSort = function( results ) {
 
 	return results;
 };
-
-} );