fix(hierarchy): reach the class attribute through className

className is an accepted selector key that no producer writes: android
reports the view class, ios the element type and the chrome dump
el.className, all of them under `class`. With no alias onto that key the
selector matched NOTHING here on every platform while the web runtime
resolved it against the live DOM, so {className: "status"} named the row
and the badge on one host and no element at all on the other.

The failure is silent: the key is accepted, so no unknown-key error
fires, and a property over the element that was never found passes
having checked nothing.

internal/hierarchy/hierarchy.go

@@ -275,6 +275,8 @@ var attributeAliases = map[string][]string{
 	"placeholderValue": {"hintText"},
 	// iOS AXElement raw name for class
 	"elementType": {"class"},
+	// DOM property name for class; every producer writes the attribute as class
+	"className": {"class"},
 }
 
 // selectorKeys is every key an object selector may use. It is the union of the