Add WebDriver support for getting elements by selector.

Also adds example support for getting the name and text properties of the elements.

components/webdriver_traits/lib.rs

@@ -12,6 +12,10 @@ use std::sync::mpsc::Sender;
 
 pub enum WebDriverScriptCommand {
     EvaluateJS(String, Sender<Result<EvaluateJSReply, ()>>),
+    FindElementCSS(String, Sender<Result<Option<String>, ()>>),
+    FindElementsCSS(String, Sender<Result<Vec<String>, ()>>),
+    GetElementTagName(String, Sender<Result<String, ()>>),
+    GetElementText(String, Sender<Result<String, ()>>),
     GetTitle(Sender<String>)
 }