CHILD positions were being cached improperly. Tweaked it and added a test to...

CHILD positions were being cached improperly. Tweaked it and added a test to make sure it doesn't happen again. Fixes jQuery bug #3924.

src/selector.js

@@ -495,7 +495,7 @@ var Expr = Sizzle.selectors = {
 		CHILD: function(elem, match){
 			var type = match[1], parent = elem.parentNode;
 
-			var doneName = "child" + parent.childNodes.length;
+			var doneName = match[0];
 			
 			if ( parent && (!parent[ doneName ] || !elem.nodeIndex) ) {
 				var count = 1;

test/unit/selector.js

@@ -141,7 +141,7 @@ test("multiple", function() {
 });
 
 test("child and adjacent", function() {
-	expect(44);
+	expect(45);
 	t( "Child", "p > a", ["simon1","google","groups","mark","yahoo","simon"] );
 	t( "Child", "p> a", ["simon1","google","groups","mark","yahoo","simon"] );
 	t( "Child", "p >a", ["simon1","google","groups","mark","yahoo","simon"] );
@@ -169,6 +169,14 @@ test("child and adjacent", function() {
 	
 	t( "First Child", "p:first-child", ["firstp","sndp"] );
 	t( "Nth Child", "p:nth-child(1)", ["firstp","sndp"] );
+
+	// Verify that the child position isn't being cached improperly
+	jQuery("p:first-child").after("<div></div>");
+	jQuery("p:first-child").before("<div></div>").next().remove();
+
+	t( "First Child", "p:first-child", [] );
+
+	reset();
 	
 	t( "Last Child", "p:last-child", ["sap"] );
 	t( "Last Child", "a:last-child", ["simon1","anchor1","mark","yahoo","anchor2","simon"] );