Removing remaining strict-mode warnings.

src/core.js

@@ -680,7 +680,7 @@ jQuery.extend({
 
 		// Return the named cache data, or the ID for the element
 		return name ?
-			jQuery.cache[ id ][ name ] :
+			jQuery.cache[ id ][ name ] || null :
 			id;
 	},
 
@@ -1163,12 +1163,12 @@ jQuery.extend({
 		// Also, we need to make sure that the correct elements are being returned
 		// (IE returns comment nodes in a '*' query)
 		if ( jQuery.browser.msie ) {
-			while ( elem = second[ i++ ] )
+			while ( (elem = second[ i++ ]) )
 				if ( elem.nodeType != 8 )
 					first[ pos++ ] = elem;
 
 		} else
-			while ( elem = second[ i++ ] )
+			while ( (elem = second[ i++ ]) )
 				first[ pos++ ] = elem;
 
 		return first;

src/event.js

@@ -40,8 +40,9 @@ jQuery.event = {
 			handle = jQuery.data(elem, "handle") || jQuery.data(elem, "handle", function(){
 				// Handle the second event of a trigger and when
 				// an event is called after a page has unloaded
-				if ( typeof jQuery !== "undefined" && !jQuery.event.triggered )
-					return jQuery.event.handle.apply(arguments.callee.elem, arguments);
+				return typeof jQuery !== "undefined" && !jQuery.event.triggered ?
+					jQuery.event.handle.apply(arguments.callee.elem, arguments) :
+					undefined;
 			});
 		// Add elem as a property of the handle function
 		// This is to prevent a memory leak with non-native

src/offset.js

@@ -131,7 +131,7 @@ jQuery.each( ['Left', 'Top'], function(i, name) {
 	var method = 'scroll' + name;
 	
 	jQuery.fn[ method ] = function(val) {
-		if (!this[0]) return;
+		if (!this[0]) return null;
 
 		return val !== undefined ?