Request w3c compliance from chrome driver

By default chromedriver is NOT compliant with the w3c spec. But one
can request w3c compliance with a capability extension included in the
new session command payload.

Author: equalsraf

src/lib.rs

@@ -16,6 +16,7 @@ extern crate serde;
 use serde::Serialize;
 use serde::de::DeserializeOwned;
 
+#[macro_use]
 extern crate serde_json;
 pub use serde_json::Value as JsonValue;
 

src/messages.rs

@@ -43,7 +43,14 @@ pub struct NewSessionCmd {
 impl NewSessionCmd {
     pub fn new() -> Self {
         NewSessionCmd {
-            capabilities: JsonValue::Object(Map::new()),
+            capabilities: json!({
+                "alwaysMatch": {
+                    // ask chrome to be w3c compliant
+                    "goog:chromeOptions": {
+                        "w3c": true
+                    }
+                }
+            }),
             desiredCapabilities: JsonValue::Object(Map::new()),
         }
     }