All: Migrate away from deprecated/removed Core APIs

Summary of the changes:

* Build: Add jQuery 3.2.0-3.4.1 to versions UI can be tested against
* Build: Load jQuery & Migrate via HTTPS
* Build: Add package-lock.json to .gitignore
* Build: Update jQuery Migrate from 3.0.0 to 3.1.0
* Build: Allow to run tests against jQuery 3.x-git
* Build: Fix formatting according to JSCS rules
* Build: Disable JSCS for the inlined jQuery Color
* All: Switch from $.isArray to Array.isArray (jQuery.isArray will be
  removed in jQuery 4.0)
* All: Switch from `$.isFunction( x )` to `typeof x === "function"`
  (jQuery.isFunction will be removed in jQuery 4.0)
* All: Inline jQuery.isWindow as it'll be removed in jQuery 4.0
* Effects: Fix a timing issue in a variable declaration. Previously,
  a jQuery object was created, chained & assigned to a variable that
  was then accessed in a callback used inside of this chained
  definition. Due to a timing difference in when the callback fired for
  the first time in latest jQuery master, it was being called before
  the variable was defined.
* Tests: Make dialog & draggable unit tests less strict (newest jQuery
  returns fractional results in some cases, making comparisons fail when
  there's a tiny difference)
* All: Migrate from $.trim to bare String.prototype.trim (jQuery.trim
  will be deprecated in jQuery 3.5)

Closes gh-1901

1 files changed, 8 insertions, 4 deletions

diff --git a/ui/position.js b/ui/position.js
index 3994e9acc..2d1969599 100644
--- a/ui/position.js
+++ b/ui/position.js
@@ -48,6 +48,10 @@ function parseCss( element, property ) {
 	return parseInt( $.css( element, property ), 10 ) || 0;
 }
 
+function isWindow( obj ) {
+	return obj != null && obj === obj.window;
+}
+
 function getDimensions( elem ) {
 	var raw = elem[ 0 ];
 	if ( raw.nodeType === 9 ) {
@@ -57,7 +61,7 @@ function getDimensions( elem ) {
 			offset: { top: 0, left: 0 }
 		};
 	}
-	if ( $.isWindow( raw ) ) {
+	if ( isWindow( raw ) ) {
 		return {
 			width: elem.width(),
 			height: elem.height(),
@@ -119,12 +123,12 @@ $.position = {
 	},
 	getWithinInfo: function( element ) {
 		var withinElement = $( element || window ),
-			isWindow = $.isWindow( withinElement[ 0 ] ),
+			isElemWindow = isWindow( withinElement[ 0 ] ),
 			isDocument = !!withinElement[ 0 ] && withinElement[ 0 ].nodeType === 9,
-			hasOffset = !isWindow && !isDocument;
+			hasOffset = !isElemWindow && !isDocument;
 		return {
 			element: withinElement,
-			isWindow: isWindow,
+			isWindow: isElemWindow,
 			isDocument: isDocument,
 			offset: hasOffset ? $( element ).offset() : { left: 0, top: 0 },
 			scrollLeft: withinElement.scrollLeft(),