Make Content-Type match spec requirements

I guess, technically, JSON can be thought of as a
kind of Javascript (after all, it's JavaScript
Object Notation), but the spec says that we should
be using `application/json`, which feels more
correct too.

Fixes a problem where the ruby remote driver did
not want to start a new session.

Author: shs96c

java/server/src/org/openqa/selenium/remote/server/AllHandlers.java

@@ -17,7 +17,8 @@
 
 package org.openqa.selenium.remote.server;
 
-import static com.google.common.net.MediaType.JAVASCRIPT_UTF_8;
+//import static com.google.common.net.MediaType.JAVASCRIPT_UTF_8;
+import static com.google.common.net.MediaType.JSON_UTF_8;
 import static java.net.HttpURLConnection.HTTP_NOT_FOUND;
 import static java.net.HttpURLConnection.HTTP_OK;
 import static java.nio.charset.StandardCharsets.UTF_8;
@@ -103,7 +104,7 @@ public void execute(HttpRequest req, HttpResponse resp) throws IOException {
           .getBytes(UTF_8);
 
       resp.setStatus(HTTP_NOT_FOUND);
-      resp.setHeader("Content-Type", JAVASCRIPT_UTF_8.toString());
+      resp.setHeader("Content-Type", JSON_UTF_8.toString());
       resp.setHeader("Content-Length", String.valueOf(payload.length));
 
       resp.setContent(payload);
@@ -121,7 +122,7 @@ public void execute(HttpRequest req, HttpResponse resp) throws IOException {
       )).getBytes(UTF_8);
 
       resp.setStatus(HTTP_OK);
-      resp.setHeader("Content-Type", JAVASCRIPT_UTF_8.toString());
+      resp.setHeader("Content-Type", JSON_UTF_8.toString());
       resp.setHeader("Content-Length", String.valueOf(payload.length));
 
       resp.setContent(payload);

java/server/src/org/openqa/selenium/remote/server/BeginSession.java

@@ -18,7 +18,7 @@
 package org.openqa.selenium.remote.server;
 
 import static com.google.common.net.HttpHeaders.CONTENT_TYPE;
-import static com.google.common.net.MediaType.JAVASCRIPT_UTF_8;
+import static com.google.common.net.MediaType.JSON_UTF_8;
 import static java.net.HttpURLConnection.HTTP_OK;
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static org.openqa.selenium.remote.BrowserType.CHROME;
@@ -150,7 +150,7 @@ public void execute(HttpRequest req, HttpResponse resp) throws IOException {
       resp.setStatus(HTTP_OK);
       resp.setHeader("Cache-Control", "no-cache");
 
-      resp.setHeader("Content-Type", JAVASCRIPT_UTF_8.toString());
+      resp.setHeader("Content-Type", JSON_UTF_8.toString());
       resp.setHeader("Content-Length", String.valueOf(payload.length));
 
       resp.setContent(payload);

java/server/src/org/openqa/selenium/remote/server/ExceptionHandler.java

@@ -17,7 +17,7 @@
 
 package org.openqa.selenium.remote.server;
 
-import static com.google.common.net.MediaType.JAVASCRIPT_UTF_8;
+import static com.google.common.net.MediaType.JSON_UTF_8;
 import static java.net.HttpURLConnection.HTTP_INTERNAL_ERROR;
 import static java.nio.charset.StandardCharsets.UTF_8;
 
@@ -56,7 +56,7 @@ public void execute(HttpRequest req, HttpResponse resp) {
     byte[] bytes = new Gson().toJson(value).getBytes(UTF_8);
     resp.setStatus(HTTP_INTERNAL_ERROR);
 
-    resp.setHeader("Content-Type", JAVASCRIPT_UTF_8.toString());
+    resp.setHeader("Content-Type", JSON_UTF_8.toString());
     resp.setHeader("Content-Length", String.valueOf(bytes.length));
 
     resp.setContent(bytes);

java/server/src/org/openqa/selenium/remote/server/Passthrough.java

@@ -17,6 +17,7 @@
 
 package org.openqa.selenium.remote.server;
 
+import static com.google.common.net.MediaType.JSON_UTF_8;
 import static java.nio.charset.StandardCharsets.UTF_8;
 import static org.openqa.selenium.remote.http.HttpMethod.POST;
 
@@ -91,7 +92,7 @@ public void handle(HttpRequest req, HttpResponse resp) throws IOException {
     if (POST == req.getMethod()) {
       // We always transform to UTF-8 on the way up.
       String contentType = req.getHeader("Content-Type");
-      contentType = contentType == null ? MediaType.JAVASCRIPT_UTF_8.toString() : contentType;
+      contentType = contentType == null ? JSON_UTF_8.toString() : contentType;
 
       MediaType type = MediaType.parse(contentType);
       connection.setRequestProperty("Content-Type", type.withCharset(UTF_8).toString());