Backing out fb6c038b, was causing jQuery.param...

Backing out fb6c038b, was causing jQuery.param tests to fail - unfixes #7413.

src/core.js

@@ -532,12 +532,6 @@ jQuery.extend({
 	},
 
 	isEmptyObject: function( obj ) {
-
-    // Fixes #7413 Check to see if obj passes isPlainObject
-    if ( !jQuery.isPlainObject( obj ) ) {
-      return false;
-    }
-	
 		for ( var name in obj ) {
 			return false;
 		}

test/unit/core.js

@@ -848,20 +848,13 @@ test("jQuery.makeArray", function(){
 });
 
 test("jQuery.isEmptyObject", function(){
-	expect(11);
+	expect(2);
 	
 	equals(true, jQuery.isEmptyObject({}), "isEmptyObject on empty object literal" );
 	equals(false, jQuery.isEmptyObject({a:1}), "isEmptyObject on non-empty object literal" );
-  equals(false, jQuery.isEmptyObject(1), "isEmptyObject on number (wrong argument type)");
-  equals(false, jQuery.isEmptyObject(0), "isEmptyObject on falsy number (wrong argument type)");  
-  equals(false, jQuery.isEmptyObject("test"), "isEmptyObject on string (wrong argument type)");
-  equals(false, jQuery.isEmptyObject(""), "isEmptyObject on falsy string (wrong argument type)");
-  equals(false, jQuery.isEmptyObject([1,2,3]), "isEmptyObject on array (wrong argument type)");
-  equals(false, jQuery.isEmptyObject([]), "isEmptyObject on an empty array (wrong argument type)");
-  equals(false, jQuery.isEmptyObject(undefined), "isEmptyObject on undefined (wrong argument type)");
-  equals(false, jQuery.isEmptyObject(false), "isEmptyObject on undefined (wrong argument type)");
-  equals(false, jQuery.isEmptyObject(null), "isEmptyObject on null (wrong argument type)" );	
 	
+	// What about this ?
+	// equals(true, jQuery.isEmptyObject(null), "isEmptyObject on null" );
 });
 
 test("jQuery.proxy", function(){