Selector: Properly implement :enabled/:disabled for select contents

SemVer patch
Fixes gh-382
Ref jquery/jquery#3224
Ref 7999a01
Closes gh-384

Author: gibson042

dist/sizzle.js

@@ -6,7 +6,7 @@
  * Released under the MIT license
  * http://jquery.org/license
  *
- * Date: 2016-02-23
+ * Date: 2016-08-08
  */
 (function( window ) {
 
@@ -465,26 +465,54 @@ function createButtonPseudo( type ) {
  * @param {Boolean} disabled true for :disabled; false for :enabled
  */
 function createDisabledPseudo( disabled ) {
-	// Known :disabled false positives:
-	// IE: *[disabled]:not(button, input, select, textarea, optgroup, option, menuitem, fieldset)
-	// not IE: fieldset[disabled] > legend:nth-of-type(n+2) :can-disable
+
+	// Known :disabled false positives: fieldset[disabled] > legend:nth-of-type(n+2) :can-disable
 	return function( elem ) {
 
-		// Check form elements and option elements for explicit disabling
-		return "label" in elem && elem.disabled === disabled ||
-			"form" in elem && elem.disabled === disabled ||
+		// Only certain elements can match :enabled or :disabled
+		// https://html.spec.whatwg.org/multipage/scripting.html#selector-enabled
+		// https://html.spec.whatwg.org/multipage/scripting.html#selector-disabled
+		if ( "form" in elem ) {
+
+			// Check for inherited disabledness on relevant non-disabled elements:
+			// * listed form-associated elements in a disabled fieldset
+			//   https://html.spec.whatwg.org/multipage/forms.html#category-listed
+			//   https://html.spec.whatwg.org/multipage/forms.html#concept-fe-disabled
+			// * option elements in a disabled optgroup
+			//   https://html.spec.whatwg.org/multipage/forms.html#concept-option-disabled
+			// All such elements have a "form" property.
+			if ( elem.parentNode && elem.disabled === false ) {
+
+				// Option elements defer to a parent optgroup if present
+				if ( "label" in elem ) {
+					if ( "label" in elem.parentNode ) {
+						return elem.parentNode.disabled === disabled;
+					} else {
+						return elem.disabled === disabled;
+					}
+				}
 
-			// Check non-disabled form elements for fieldset[disabled] ancestors
-			"form" in elem && elem.disabled === false && (
-				// Support: IE6-11+
-				// Ancestry is covered for us
-				elem.isDisabled === disabled ||
+				// Support: IE 6 - 11
+				// Use the isDisabled shortcut property to check for disabled fieldset ancestors
+				return elem.isDisabled === disabled ||
 
-				// Otherwise, assume any non-<option> under fieldset[disabled] is disabled
-				/* jshint -W018 */
-				elem.isDisabled !== !disabled &&
-					("label" in elem || !disabledAncestor( elem )) !== disabled
-			);
+					// Where there is no isDisabled, check manually
+					/* jshint -W018 */
+					elem.isDisabled !== !disabled &&
+						disabledAncestor( elem ) === disabled;
+			}
+
+			return elem.disabled === disabled;
+
+		// Try to winnow out elements that can't be disabled before trusting the disabled property.
+		// Some victims get caught in our net (label, legend, menu, track), but it shouldn't
+		// even exist on them, let alone have a boolean value.
+		} else if ( "label" in elem ) {
+			return elem.disabled === disabled;
+		}
+
+		// Remaining elements are neither :enabled nor :disabled
+		return false;
 	};
 }
 
@@ -1693,6 +1721,7 @@ function addCombinator( matcher, combinator, base ) {
 					return matcher( elem, context, xml );
 				}
 			}
+			return false;
 		} :
 
 		// Check against all ancestor/preceding elements
@@ -1737,6 +1766,7 @@ function addCombinator( matcher, combinator, base ) {
 					}
 				}
 			}
+			return false;
 		};
 }