Fix #12733. Ignore excess spaciness in event strings.

Thanks @bentruyman!

src/event.js

 var rformElems = /^(?:textarea|input|select)$/i,
 	rtypenamespace = /^([^\.]*|)(?:\.(.+)|)$/,
+	reventTypes = /\S+/g,
 	rkeyEvent = /^key/,
 	rmouseEvent = /^(?:mouse|contextmenu)|click/,
 	rfocusMorph = /^(?:focusinfocus|focusoutblur)$/;
@@ -52,7 +53,7 @@ jQuery.event = {
 
 		// Handle multiple events separated by a space
 		// jQuery(...).bind("mouseover mouseout", fn);
-		types = jQuery.trim( types ).split( " " );
+		types = (types || "").match( reventTypes ) || [""];
 		for ( t = 0; t < types.length; t++ ) {
 
 			tns = rtypenamespace.exec( types[t] ) || [];
@@ -135,7 +136,7 @@ jQuery.event = {
 		}
 
 		// Once for each type.namespace in types; type may be omitted
-		types = jQuery.trim( types ).split(" ");
+		types = (types || "").match( reventTypes ) || [""];
 		for ( t = 0; t < types.length; t++ ) {
 			tns = rtypenamespace.exec( types[t] ) || [];
 			type = origType = tns[1];

test/unit/event.js

@@ -2650,7 +2650,7 @@ test(".on and .off", function() {
 		counter += (e.data || 0) + (trig || 1);
 	};
 	jQuery( "#onandoff" )
-		.on( "click clack cluck", "em", 2, mixfn )
+		.on( " click  clack cluck ", "em", 2, mixfn )
 		.on( "cluck", "b", 7, mixfn )
 		.on( "cluck", mixfn )
 		.trigger( "what!" )