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, 2 insertions, 2 deletions

diff --git a/ui/widgets/droppable.js b/ui/widgets/droppable.js
index 89bff2511..f98ff2714 100644
--- a/ui/widgets/droppable.js
+++ b/ui/widgets/droppable.js
@@ -57,7 +57,7 @@ $.widget( "ui.droppable", {
 		this.isover = false;
 		this.isout = true;
 
-		this.accept = $.isFunction( accept ) ? accept : function( d ) {
+		this.accept = typeof accept === "function" ? accept : function( d ) {
 			return d.is( accept );
 		};
 
@@ -109,7 +109,7 @@ $.widget( "ui.droppable", {
 	_setOption: function( key, value ) {
 
 		if ( key === "accept" ) {
-			this.accept = $.isFunction( value ) ? value : function( d ) {
+			this.accept = typeof value === "function" ? value : function( d ) {
 				return d.is( value );
 			};
 		} else if ( key === "scope" ) {